Autograph, A Package of Routines to Draw X/Y Plots

This is the unabridged write-up of AUTOGRAPH: a graphics package enabling the user to draw graphs, each with a labelled background and each displaying one or more curves.

This write-up is divided into several major sections: The section "OVERVIEW" presents the philosophy of the package and should eventually be read by a serious user. The section "ROUTINES" describes the various routines in the package and how to call them. The section "PARAMETERS" describes the "control parameters" which govern the behavior of AUTOGRAPH. The section "EXAMPLES" explains how to get a set of graphs produced by AUTOGRAPH and the programs which produced them. The section "MESSAGES" describes messages that accompany the possible error exits.

Each major section is divided into titled paragraphs, which are further divided into untitled paragraphs. In general, phrases like "the preceding paragraph" or "the following paragraph" are to be interpreted to refer to a titled paragraph.

Readers who wish only to quickly draw a simple graph may want to skip to the descriptions of the routines EZY, EZXY, EZMY, and EZMXY, in the section "ROUTINES". Others may wish to look first at the examples.

OVERVIEW

This section describes the philosophy of AUTOGRAPH.

How to Draw a Graph

To draw a graph, a user program executes, directly or indirectly, a series of calls to AUTOGRAPH routines, typically as follows:

The routines AGSETC, AGSETF, AGSETI, AGSETP, and/or AGSETR are called to reset "primary control parameters" having unsatisfactory values.
The routine AGSTUP is called to perform "set-up" tasks (hence the name). It computes appropriate values for the "secondary control parameters".
The routine AGBACK is called to draw a background.
The routine AGCURV is called one or more times (once per curve) to draw the desired curves.
The system-plot-package routine FRAME is called to advance to a new frame.

To draw the next graph, all five steps are repeated; step 1 may be abbreviated or omitted entirely.

A Simpler Way to Draw a Graph

Each of the routines EZY, EZXY, EZMY, and EZMXY performs a sequence of calls like that described above. A user program may call

EZY to graph a single curve defined by the points (I,Y(I)), for I from 1 to N,
EZXY to graph a single curve defined by the points (X(I),Y(I)), for I from 1 to N,
EZMY to graph the M curves defined by the points (I,Y(I,J)), for I from 1 to N and J from 1 to M, and
EZMXY to graph the M curves defined by the points (X(I),Y(I,J)) or (X(I,J),Y(I,J)), for I from 1 to N and J from 1 to M.

See the descriptions of these routines, in the section "ROUTINES". See also examples from "agex01" through "agex04".

The AUTOGRAPH Control Parameters

The labeled common block AGCONP contains the AUTOGRAPH "control parameters", each of which controls some aspect of the package's behavior. There are two types of these: "primary control parameters" and "secondary control parameters".

Each primary control parameter has a default value and is subject to change by a user program to produce a desired effect.
Each secondary control parameter is computed by AUTOGRAPH itself and is not normally subject to direct change by a user program. The values computed for some of the secondary control parameters may be of interest and may be retrieved by a user program.

Access to the control parameters is provided by the routines AGGETC, AGGETF, AGGETI, AGGETP, AGGETR, AGSETC, AGSETF, AGSETI, AGSETP, and AGSETR. (The routines ANOTAT and DISPLA provide access to a limited subset of the control parameters and are provided principally for historical reasons; they are of interest mainly to users of the routines EZY, EZXY, EZMY, and EZMXY.)

In the rest of this document, the long phrase "primary control parameter" will usually be shortened to just "parameter".

Control Parameter Names

There are many groups of parameters. Each group has a keyword associated with it - like BACKGROUND or GRAPH or AXIS. Those groups which contain more than one parameter are divided into subgroups, each of which also has a keyword associated with it. The subgroups may be further subdivided in the same manner.

Group keywords are used to make up names of parameter groups and, ultimately, of individual parameters. This is done by stringing together the group keywords, in descending order, separated by slashes and terminated by a period. For example, the name 'AXIS.' refers to a group of 92 parameters describing the four axes, the name 'AXIS/LEFT.' to a subgroup of 23 parameters describing the left axis, the name 'AXIS/LEFT/NUMERIC.' to a further subgroup of 8 parameters describing the numeric labels on the left axis, and the name 'AXIS/LEFT/NUMERIC/TYPE.' to a single parameter describing the type of numeric labels on the left axis.

Parameter-group names are used as arguments in calls to parameter-access routines to identify the parameter(s) whose values a user program wishes to "set" or "get". For example, the statement

      CALL AGSETR ('AXIS/LEFT/NUMERIC/TYPE.',1.)

is used to set the value of the parameter specifying the type of numeric labels to be used on the left axis to "1.".

Parameter-group names may be shortened considerably, both by abbreviation of the keywords and by omission of some keywords; for example, the name shown above may be shortened to 'LE/TY.'.

Complete information about the control parameters and their names is given below, in the section "PARAMETERS".

Control Parameters are Reals

All of the control parameters are of type REAL - even those which serve as type specifiers, control flags, item counts, list pointers, and the like - for which integer variables would normally be used. This was done because of a portability problem which arose in implementing the parameter-access routines.

Those parameters which may only have discrete integral values are referenced internally using the FORTRAN function IFIX. For example: The parameter 'X/NICE.' corresponds to a variable in the common block AGCONP named QCEX, which may have any of the values "-1.", "0.", or "+1.". The function IFIX(QCEX) is used by AUTOGRAPH to recover the integer value.

Conceptually, some parameters have character-string values; for example, the parameter 'DASH/PATTERN/1.' may, conceptually, have the value '$$$$$1$$$$$'. Obviously, one must come up with a scheme which will allow any possible character string to be represented as a real number. At one time, the real equivalent of the memory address of the character string was used as the actual value of the parameter. This approach led to portability problems and has been abandoned in favor of the following: A character string which is to become the conceptual value of a parameter is stashed in a character-string array inside AUTOGRAPH and a real identifier which will enable later retrieval of the string is stored as the actual value of the parameter. (As it happens, such identifiers are always negative; positive values may therefore have other uses. For example, if 'DASH/PATTERN/1.' has a negative value, a character-string dash pattern is implied, but, if it has a positive value, a 16-bit binary dash pattern is implied.)

Use of Parameter-Access Routines

The routine AGSETP (AGGETP) is called by a user program to "set" ("get") the real values of a group of related parameters.

The routine AGSETR is used to store a real number as the value of a single parameter and the routine AGGETR is used to retrieve the real value of a single parameter. (For historical reasons, equivalent routines AGSETF and AGGETF are provided, as well.)

The routine AGSETI is used to store the real equivalent of an integer as the value of a single parameter and the routine AGGETI is used to retrieve the integer equivalent of the value of a single parameter.

The routine AGSETC is used to store a character string as the (conceptual) value of a single parameter and the routine AGGETC is used to retrieve the (conceptual) character-string value of a single parameter.

Side Effects of Parameter-Setting

Setting certain individual parameters results, as a side effect, in "special action" by the routine AGSETP. For example, when 'BACKGROUND.' is given a new value, other parameters are also changed to create the desired background. These side effects occur whether AGSETP is reached directly from the user program or indirectly, by way of a call to one of the routines AGSETC, AGSETF, AGSETI, or AGSETR. They do not occur when AGSETP is asked to set one of the parameters in question as part of a multi-parameter group, only when it is asked to set that parameter individually.

Saving and Restoring Defaults

Parameters whose values have been changed by the user do not automatically revert to their default values. Re-creating the default state of AUTOGRAPH by resetting individual parameters can become quite tedious. The routines AGSAVE, which saves the current state of AUTOGRAPH in a file, and AGRSTR, which restores a saved state of AUTOGRAPH from a file, should be used instead. These routines are described in the section "ROUTINES".

Special Values 'NULL/1.' and 'NULL/2.'

The parameters 'NULL/1.' and 'NULL/2.' define the special values "null 1" and "null 2", which have the default values "1.E36" and "2.E36", respectively. These special values are used in a couple of ways:

Certain parameters may be given an "actual" value or one of the "null" values. An actual value directly expresses the value of some quantity. The value "null 1" specifies that AUTOGRAPH is to choose an appropriate value to use, but that it is not to store that value in place of the "null 1". The value "null 2" specifies that AUTOGRAPH is to choose an appropriate actual value and store that actual value in place of the "null 2".

: Example: 'Y/MINIMUM.', which specifies the minimum Y coordinate, has the default value "null 1", specifying that, for each graph, AUTOGRAPH is to choose (by examining the data) an appropriate minimum Y. This parameter may be given an actual (non-null) value, thus imposing a desired minimum Y, or it may be given the value "null 2", specifying that AUTOGRAPH is to choose an appropriate minimum Y for the next graph and then use that value for following graphs.

The value "null 1" is used in X/Y coordinate data to signal missing points.

Note: Because of the second possibility mentioned above, if your X/Y coordinate data might include the values "1.E36" or "2.E36", your program's first action should be to change the values of 'NULL/1.' and 'NULL/2.' to values which cannot possibly occur in the data.

The Graph Window

The parameters 'GRAPH/LEFT.', 'GRAPH/RIGHT.', 'GRAPH/BOTTOM.', and 'GRAPH/TOP.' serve to locate the edges of a rectangular "graph window" within the plotter frame. The first two are stated as fractions of the frame width, the second two as fractions of the frame height. These parameters have the default values "0.", "1.", "0.", and "1., respectively, specifying a graph window which fills the entire plotter frame.

The graph window is the area in which a graph, including labels, is to be drawn. A user program may limit a graph to any selected portion of the plotter frame. For example, changing the values of the parameters in the group 'GRAPH.' to "0.", ".5", "0.", and ".5", limits a graph to the lower left-hand quarter of the frame.

See example "agex06".

The Grid Window

The parameters 'GRID/LEFT.', 'GRID/RIGHT.', 'GRID/BOTTOM.', and 'GRID/TOP.' serve to locate the edges of a rectangular area within the graph window; the parameter 'GRID/SHAPE.' specifies the shape of a "grid window", to be centered in, and made as large as possible in, this rectangular area. The positions of the left and right edges are stated as fractions of the graph-window width and have default values ".15" and ".95"; the positions of the bottom and top edges are stated as fractions of the graph-window height and also have default values ".15" and ".95". The parameter 'GRID/SHAPE.' has the default value "0.", specifying a grid window which completely fills the area specified by the other parameters. Other values allow one to specify a grid window of any desired rectangular shape or of a shape implied by the X and Y coordinate data.

The grid window is the portion of the graph window along the edges of which the axes are to be drawn and within which curves are to be drawn. Numeric and informational labels are ordinarily placed in the portion of the graph window which is outside the grid window. Various positioning parameters are stated in a "grid coordinate system" based on the grid window and curve-point coordinates are given by the user in a "user coordinate system" which maps into the grid window. If 'WINDOW.' has the value "1.", only those curve portions which lie inside the grid window are drawn. Character sizes and label-offset distances are specified as fractions of the smaller dimension of the grid window, so as to be in scale with the rest of the graph.

The routine AGSTUP calls the SPPS routine SET to define the mapping from a window in "user-coordinate" space to a viewport in "fractional-coordinate" space. AUTOGRAPH's grid window is synonymous with that viewport.

See example "agex07".

The Grid Coordinate System

Internally, AUTOGRAPH makes use of a "grid coordinate system"; the user also makes use of this system at times in setting certain parameter values. The origin of the grid coordinate system is at the lower left-hand corner of the grid window. X coordinates run linearly from "0." to "1." horizontally, and Y coordinates linearly from "0." to "1." vertically, in the grid window. Note that coordinate values outside the range (0.,1.) may be used to reference points outside the grid window.

The User Coordinate System

Curve-defining points are stated by a user program in the "user coordinate system". Fourteen parameters specify how that user coordinate system is mapped into the grid window. (The parameter 'INVERT.', described below, might be considered a fifteenth.)

The first seven of the fourteen, named 'X/MINIMUM.', 'X/MAXIMUM.', 'X/LOGARITHMIC.', 'X/ORDER.', 'X/NICE.', 'X/SMALLEST.', and 'X/LARGEST.', specify how user X coordinates are to be mapped onto the horizontal axis of the grid window. The default values of these parameters are such that the routine AGSTUP is forced to:

Compute, from the user's X-coordinate data, minimum and maximum values X_m and X_M.
Compute "nice" (rounded) values X_m' and X_M' such that the interval (X_m,X_M) is completely contained in the interval (X_m',X_M').
Map X_m' to the left edge, and X_M' to the right edge, of the grid window. The mapping is linear.

The other seven parameters, named 'Y/MINIMUM.', 'Y/MAXIMUM.', etc., specify how user Y coordinates are to be mapped onto the vertical axis of the grid window. The default values specify a mapping analogous to that of X coordinates.

By changing the values of these fourteen parameters appropriately, a variety of desirable ends may be achieved:

Values of X_m, X_M, Y_m, and/or Y_M may be specified, thus limiting the graph to a particular range of interest and/or forcing consistent scaling of a group of graphs. If the selection of these values is left up to AUTOGRAPH, a range of acceptable values may be specified.
Either or both mappings may be made logarithmic. (The logarithms of coordinate values are mapped linearly onto the axis.)
Either or both mappings may be flipped end-for-end. X coordinates may be made to decrease from left to right, Y coordinates to decrease from bottom to top.
The rounding process for either or both mappings may be suppressed, forcing curves to be plotted full-scale.

The call to the SPPS routine SET that is done by AGSTUP reflects the current values of all the parameters in the groups 'X.' and 'Y.', as described above.

See examples "agex06", "agex07" , and "agex08".

How to Graph "X as a Function of Y"

The parameter 'INVERT.' has the default value "0.". If it is set to "1." by a user program, the routines AGSTUP and AGCURV will behave as if their X and Y arguments had been interchanged. In some sense, this provides a way of plotting "X as a function of Y".

This parameter is of principal interest to the users of EZY, EZXY, EZMY, and EZMXY; those users who call the routines AGSTUP and AGCURV directly should probably leave the parameter zeroed.

See example "agex08".

What a Background Consists of

A background drawn by the routine AGBACK consists of four axes and up to eight informational labels, each of the latter having none or more lines of text; the total number of such lines must not exceed sixteen. Each of these entities is defined by a group of parameters and may be modified in a variety of ways.

The Four Axes

The four axes are positioned along the edges of the grid window. There are a left Y axis, a right Y axis, a bottom X axis, and a top X axis. Each of the axes consists of a line, major tick marks, minor tick marks, and numeric labels. Numeric labels are placed at major-tick-mark positions.

The axes are defined by the parameter group named 'AXIS.', which has subgroups 'AXIS/LEFT.', 'AXIS/RIGHT.', 'AXIS/BOTTOM.', and 'AXIS/TOP.'. Each of these subgroups contains 23 parameters defining one of the four axes. These 23 parameters fall into six further subgroups, having the associated keywords "CONTROL", "LINE", "INTERSECTION", "FUNCTION", "TICKS", and "NUMERIC".

The default values of the axis parameters specify a "perimeter" background: All four axes are drawn; each has short, inward-pointing major and minor ticks; the left axis and the bottom axis have numeric labels (placed outside the grid window); the right-axis and top-axis numeric labels are suppressed. See examples "agex01" through "agex04" .

A "half-axis" background is created by suppressing the right axis and the top axis completely. A "grid" background is created by extending the left-axis and bottom-axis ticks all the way across the grid window and suppressing the ticks on the other two axes. The parameter 'BACKGROUND.' allows the user to create these standard backgrounds easily; whenever its value is changed by a user-program call to AGSETI, AGSETF, AGSETP, or AGSETR, parameters in the group 'AXIS.' are modified to create the desired background.

See examples "agex05", "agex06" , and "agex08".

Abbreviated Form of Axis-Parameter Names

In the ensuing discussions of the various parameters in the group 'AXIS.', the character "s" is used to stand for any one of the keywords "LEFT", "RIGHT", "BOTTOM", or "TOP". For example, 'AXIS/s/LINE.' stands for any one of 'AXIS/LEFT/LINE.', 'AXIS/RIGHT/LINE.', etc. This form is shorter and makes it clear that four different parameters or groups of parameters are being described at once.

The Parameter 'AXIS/s/CONTROL.'

This parameter may be given any integral value from "-1." to "+4.":

The value "-1." specifies that only the line portion of the axis specified by "s" is to be drawn.
The value "0." specifies that no portion of the axis is to be drawn.
A value from "1." to "4." specifies that all portions of the axis are to be drawn and tells AUTOGRAPH what liberties it may take in attempting to cope with numeric labels which will not fit along the axis without overlapping.

The precise meanings of each value are described in the section "PARAMETERS".

The Parameter 'AXIS/s/LINE.'

This parameter has the default value "0.". Setting it to a "1." causes the line portion of the axis specified by "s" to be suppressed. Tick marks and/or numeric labels may still be drawn.

Moving an Axis

Both of the parameters

      'AXIS/s/INTERSECTION/GRID.'
      'AXIS/s/INTERSECTION/USER.'

have the default value "null 1", specifying that the axis "s" is to be drawn in its normal position, along the edge of the grid window. If either parameter is given a non-null value, the axis "s" is moved away from its normal position in such a way as to intersect the sides of the grid which are perpendicular to it at a point specified by that non-null value. To move an X axis, a Y coordinate is specified; to move a Y axis, an X coordinate is specified.

The coordinate may be specified in the grid coordinate system or in the user coordinate system, depending on which parameter is used. If both parameters are given non-null values, the user-system value takes precedence.

No axis may be moved outside the graph window. Attempting to do so moves the axis as far as the edge, but no farther.

See example "agex08".

The "Label Coordinate System" Along an Axis

Each of the four axes has associated with it a "user" coordinate system (as described above, in the paragraph "THE USER COORDINATE SYSTEM") and a "label" coordinate system. The routine AGUTOL defines the relationship between the two coordinate systems for each of the four axes.

Tick marks are positioned at "nice" values in the label coordinate system, mapped to the user coordinate system, and then mapped onto the axis. Numeric labels are associated with major ticks and provide values in the label coordinate system.

The default version of AGUTOL defines the label system on each axis to be identical with the user system; a private version of AGUTOL may be substituted in place of the default one in order to change the label coordinate system for any one or more of the four axes. (Usually, this can be done by simply compiling one's own version, in which case the loader will use it rather than the one inside AUTOGRAPH.)

Example: Suppose that the Y-coordinate data is in miles/hour and it is desired that the left Y axis be tick-marked and labeled in meters/second. The user program must include a subroutine AGUTOL with five arguments (four input, one output), as follows:

the number of the axis being drawn (1, 2, 3, or 4, implying the left, right, bottom, and top axes, respectively)
the value of 'AXIS/s/FUNCTION.' for that axis
an integer specifying whether to map from the user system to the label system (+1) or vice-versa (-1)
an input value in one coordinate system
an output value in the other system

The user routine must, for the left axis only, multiply the input value by the appropriate constant and return the result as the output value; for all other axes, it must return an output value equal to the input value.

It is recommended that the default value of 'AXIS/s/FUNCTION.' (zero) be used to imply that AGUTOL should do the identity mapping for the axis "s"; other values may be used to select desired mappings. This gives a way to "turn off" the use of a special mapping for a given axis.

Note that the tick-marking and labeling of one X (Y) axis of a graph may be completely different from that of the other X (Y) axis of the graph. For example, the left Y axis could be made to indicate "height in kilometers" and the right Y axis "pressure in millibars".

See example "agex07".

Positioning of Major Tick Marks on an Axis

The parameter group named

      'AXIS/s/TICKS/MAJOR/SPACING.'

contains three parameters, with associated keywords TYPE, BASE, and COUNT. These parameters are described in detail in the section "PARAMETERS". Major tick marks may be spaced linearly or logarithmically in the label coordinate system along the axis specified by "s", or suppressed altogether. Each of the TYPE and BASE parameters has the default value "null 1", allowing AUTOGRAPH to position major tick marks as it sees fit.

See examples "agex07", "agex08" and "agex13".

Appearance of Major Tick Marks

The parameter

      'AXIS/s/TICKS/MAJOR/PATTERN.'

has an integral value from "0." to "65535." and specifies the dashed-line pattern to be used for major ticks on the axis specified by "s". Each "0" bit in the lower 16 bits of the integral value specifies a gap 3 plotter units long, each "1" bit a solid portion 3 plotter units long. The default value "65535." (2¹⁶-1) specifies a solid line. The value "0." may be used to suppress major tick marks on the axis "s".

The parameters

      'AXIS/s/TICKS/MAJOR/LENGTH/OUTWARD.'
      'AXIS/s/TICKS/MAJOR/LENGTH/INWARD.'

specify the lengths of the outward-pointing and inward-pointing portions of the major ticks. Each is stated as a fraction of the smaller dimension of the grid window. If either of these values is made greater than or equal to "1.", it specifies a tick-mark portion which extends to the edge of the grid window and a little beyond, the magnitude of the "little beyond" being specified by the fractional portion of the parameter value; this can be used to create grids. The default values give inward-pointing major ticks of length ".015" on all axes.

See example "agex08".

Positioning and Appearance of Minor Tick Marks

The parameter

      'AXIS/s/TICKS/MINOR/SPACING.'

specifies the number of minor ticks which are to occur between pairs of major ticks on the axis specified by "s". Minor ticks are equidistantly spaced in the label coordinate system for that axis. The default value of this parameter is "null 1", allowing AUTOGRAPH to position minor ticks as it sees fit.

The parameters

      'AXIS/s/TICKS/MINOR/PATTERN.'
      'AXIS/s/TICKS/MINOR/LENGTH/OUTWARD.'
      'AXIS/s/TICKS/MINOR/LENGTH/INWARD.'

specify the dashed-line pattern, outward-pointing length, and inward-pointing length of minor ticks. They are defined in the same way as the analogous major-tick parameters, except that the default inward-pointing tick length is ".010".

See example "agex13".

Numeric Labels on an Axis

The parameter group named 'AXIS/s/NUMERIC.' contains eight parameters describing the numeric labels on the axis specified by "s". These parameters are described in detail in the section "PARAMETERS"; they are described sketchily in succeeding paragraphs.

Types of Numeric Labels

The parameter named 'AXIS/s/NUMERIC/TYPE.' may be given any integral value from "0." to "3." or one of the values "null 1" or "null 2".

The value "0." suppresses numeric labels on the axis specified by "s".
The values "1.", "2.", and "3." specify the use of "scientific notation", "exponential notation", and "no-exponent notation", respectively.
A null value gives AUTOGRAPH the freedom to use one of the values "1.", "2.", or "3." - whichever is most consistent with the label coordinate system along the axis.

The exact nature of the labels produced by a given value depends on the three parameters

      'AXIS/s/TICKS/MAJOR/SPACING/TYPE.'
      'AXIS/s/NUMERIC/EXPONENT.'
      'AXIS/s/NUMERIC/FRACTION.'

See examples "agex07" and "agex13".

Orientation of Numeric Labels

The parameters

      'AXIS/s/NUMERIC/ANGLE/1ST.'
      'AXIS/s/NUMERIC/ANGLE/2ND.'

may have integral values "0.", "90.", "180.", or "270.". They specify the user's first and second choices for the orientation of numeric labels on the axis specified by "s". AUTOGRAPH will attempt to use the first choice (default value: "0." for all axes); if that leads to overlap problems and shrinking the labels either doesn't help or is not permitted and rotation is permitted (by the setting of 'AXIS/s/CONTROL.'), AUTOGRAPH may try the second choice (default value: "90." for all axes).

The values given represent angles measured in degrees counter-clockwise from horizontal.

Positioning of Numeric Labels

The parameter

      'AXIS/s/NUMERIC/OFFSET.'

specifies on which side of the axis specified by "s" the numeric labels are to lie and the size of the gap to be left between the axis line and the numeric labels:

A negative value specifies labels inside the grid window.
A zero value specifies labels centered on the axis, suppresses the line portion of the axis, and moves the inward-pointing and outward-pointing portions of ticks out away from the axis so as to leave room for the labels.
A positive value specifies labels outside the grid window.

The magnitude of the value specifies the distance from the axis to the nearest portion of the label, stated as a fraction of the smaller side of the grid window.

The default value for all axes is ".015".

Character Sizes in Numeric Labels

The parameters

      'AXIS/s/NUMERIC/WIDTH/MANTISSA.'
      'AXIS/s/NUMERIC/WIDTH/EXPONENT.'

specify the widths of characters in the mantissa and exponent portions of the numeric labels on the axis specified by "s", stated as fractions of the smaller dimension of the grid window.

The sizes specified are those desired by the user. If an overlap problem arises and 'AXIS/s/CONTROL.' is set so as to allow AUTOGRAPH to shrink the numeric labels, the characters may end up smaller than desired. No character is shrunk to less than the minimum readable size, however.

These parameters have default values ".015" and ".010", respectively, for all axes.

Informational Labels

As many as m informational labels may be defined at any one time; normally, m = 8. The informational labels form a part of the background produced by a call to the routine AGBACK. Each of the informational labels is defined as follows:

Each label has a name - a short character string which uniquely identifies the label.
Each label has a "suppression flag", which may be set to enable or disable plotting of the label.
Each label is positioned relative to a "basepoint", whose X and Y coordinates are specified in the grid coordinate system. Normally, the basepoint lies on one edge - but not at a corner point - of the grid window.
Emanating from the label basepoint is an "offset vector", whose X and Y components are specified as signed fractions of the smaller dimension of the grid window. Normally, the offset vector is used to specify the size of the gap to be left between an informational label and the edge of the grid window. The presence or absence of an axis along that edge of the grid window is ignored when specifying this gap; see the paragraph "BACKGROUND OVERLAP PROBLEMS", below.
Emanating from the end of the offset vector is a "baseline", whose direction is specified as an angle in degrees ("0.", "90.", "180.", or "270.", measured counter-clockwise from horizontal). The text lines of a label are written parallel to, and in the same direction as, the baseline.
A centering option for each label determines whether the left edges, the centers, or the right edges of the text lines are aligned with the end of the offset vector.

Each label may contain one or more text lines (or none). The total number of text lines in all labels must not exceed n - normally, n = 16. Each of the text lines is defined as follows:

Each text line has an integral position number which distinguishes it from every other line in the same label. Multiples of "100." are recommended. Lines with positive position numbers are drawn above the label baseline, lines with negative position numbers below the label baseline. A line with position number "0." is centered on the label baseline. ("Above" and "below" are defined here from the viewpoint of a reader of the label.) The position numbers of the lines in a label specify the order in which the lines appear - strictly decreasing from top to bottom - but do not determine the interline spacing, which is set by AUTOGRAPH itself.
Each line has a "suppression flag", which may be set so as to enable or disable drawing of the line.
Each line has a character-width specifier, stated as a fraction of the smaller dimension of the grid window.
The text of each line is defined by a character string and a count of the number of characters in the string - normally determined by AUTOGRAPH itself.

Note: The string replacements

      'FLLB(10,8)' => 'FLLB(10,m)'
      'QBIM / 8.' => 'QBIM / m.'

where "m" is greater than or equal to 5, may be applied to the AUTOGRAPH source file to provide for a maximum of "m" labels. Similarly, the string replacements

      'FLLN(6,16)' => 'FLLN(6,n)'
      'QNIM / 16.' => 'QNIM / n.'

where "n" is greater than or equal to 5, may be applied to the AUTOGRAPH source file to provide for a maximum of "n" lines.

The Predefined Labels

The section "PARAMETERS" describes in detail four "predefined" labels, named 'R', 'L', 'B', and 'T'. Each of these labels lies along one of the four edges of the grid window - the left edge, the right edge, the bottom edge, or the top edge.

The predefined labels greatly simplify the task of generating labels along the edges of the grid window. For example, if you want a "header label" above the grid window, you need only specify the desired character string to define the text of line number "100." of the label named 'T'.

The default definitions of the predefined labels specify a label reading "X" below the grid window and a label reading "Y" to the left of the grid window.

See examples "agex05", "agex07" , and "agex13".

The Parameter Group 'LABEL.'

The parameter group 'LABEL.' contains 10m+3 parameters - normally, m = 8. Together with the parameters in the group 'LINE.', they define the informational labels to be drawn by a call to the routine AGBACK. The parameters in the group 'LABEL.' are as follows:

The parameter 'LABEL/CONTROL.' may be given the value "-1." to delete all currently-defined labels, the value "0." to temporarily disable the drawing of labels, the value "1." to enable the drawing of labels and prevent the shrinkage of labels when overlap problems arise, or the value "2." to enable the drawing of labels and allow shrinkage. The default value is "2.". See examples "agex05" and "agex06".
The parameter 'LABEL/BUFFER/LENGTH.' should not normally be set by a user program. Its value is m, the maximum number of labels AUTOGRAPH can handle.
The subgroup 'LABEL/BUFFER/CONTENTS.' consists of 10m words, in which the label definitions are stored. Normally, a user program should not attempt to store values in this block directly. See the paragraph "ACCESSING A LABEL DEFINITION", below.
The parameter 'LABEL/NAME.' is used in the process of accessing a label definition. It functions as a switch, pointing to the label definition currently being accessed.

See examples "agex05", "agex07", and "agex13".

See the section "PARAMETERS" for further information about these parameters.

The Parameter Group 'LINE.'

The parameter group 'LINE.' contains 6n+4 parameters - normally, n = 16. They define the lines belonging to the various labels. The parameters in the group 'LINE.' are as follows:

The parameters 'LINE/MAXIMUM.' and 'LINE/END.' define the assumed maximum line length (default - 40 characters) and the line end character (default - '$'). These parameters come into play when a user program defines the text of a line. The character string tendered by the user is assumed to be of maximum length; if it is really shorter than that, it must be followed by the line end character. See the examples "agex08" and "agex13" .
The parameter 'LINE/BUFFER/LENGTH.' should not normally be set by a user program. Its value is n, the maximum number of lines AUTOGRAPH can handle.
The subgroup 'LINE/BUFFER/CONTENTS.' consists of 6n words, in which the line definitions are stored. Normally, a user program should not attempt to store values in this block directly. See the paragraph "ACCESSING A LINE DEFINITION", below.
The parameter 'LINE/NUMBER.' is used in the process of accessing a line definition. It functions as a switch, pointing to the line definition currently being accessed.

See the section "PARAMETERS" for further information about these parameters.

See the examples "agex05", "agex07" , and "agex13".

Accessing a Label Definition

To access a label definition, a user program must first execute an AGSETC call to store the name of the label as the value of 'LABEL/NAME.'. Such a call does not actually store the name as the value of that parameter. Instead, it causes the label buffer to be searched for the definition of the named label. If that definition is not found, a default definition is made up and inserted in the label buffer. In any case, the index of the definition is floated and stored as the value of the parameter 'LABEL/NAME.'.

Once 'LABEL/NAME.' has been set in this manner, the parameter group name 'LABEL/DEFINITION.' and subgroup names of the form 'LABEL/DEFINITION/...' may be used to access the parameters defining the label. These parameters are as follows:

The parameter 'LABEL/DEFINITION/SUPPRESSION.' may be given the value "-2." to delete the label and all of its lines, the value "-1." to delete the lines of the label but leave the label itself defined, the value "0." to enable drawing of the label, and the value "1." to temporarily suppress drawing of the label. It has the default value "0.". When a label is deleted, 'LABEL/NAME.' and 'LINE/NUMBER.' become undefined; similarly, when the lines of a label are deleted, 'LINE/NUMBER.' becomes undefined.
The parameters 'LABEL/DEFINITION/BASEPOINT/X.' and '...Y.' specify the coordinates, in the grid coordinate system, of the label's basepoint. The default basepoint is (.5,.5).
The parameters 'LABEL/DEFINITION/OFFSET/X.' and '...Y.' specify the components of the label's offset vector, as signed fractions of the smaller dimension of the grid window. The default vector has zero components.
The parameter 'LABEL/DEFINITION/ANGLE.' specifies the angle ("0.", "90.", "180.", or "270.") at which the label's baseline emanates from the end of its offset vector. The default angle is "0.".
The parameter 'LABEL/DEFINITION/CENTER.' has the value "-1." to align the left ends, the value "0." to align the centers, and the value "+1." to align the right ends, of the lines of the label with the end of its offset vector. The default value is "0.".
The parameters 'LABEL/DEFINITION/LINES.' and 'LABEL/DEFINITION/INDEX.' are not normally set by a user program; they are maintained by AUTOGRAPH. The former specifies the number of lines belonging to the label and the latter specifies the index (in the line buffer) of the definition of the first line belonging to the label. A default label has no lines - both of these parameters are zeroed.

See the section "PARAMETERS" for further information about these parameters.

See examples "agex05", "agex07" , and "agex13".

Accessing a Line Definition

To access the definition of one of the lines of a label, a user program must first access the label definition by setting 'LABEL/NAME.', as described above. Then, it must execute an AGSETP (or AGSETI) call to store the number of the desired line as the value of 'LINE/NUMBER.'. Such a call does not actually store the specified number as the value of that parameter. Instead, it causes the line buffer to be searched for the definition of the desired line. If that definition is not found, a default definition is made up, inserted in the line buffer, and added to the linked list of definitions of lines belonging to the label. In any case, the index of the definition is floated and stored as the value of 'LINE/NUMBER.'.

Once 'LINE/NUMBER.' has been set in this manner, the parameter group name 'LINE/DEFINITION.' and subgroup names of the form 'LINE/DEFINITION/...' may be used to access the parameters defining the line. These parameters are as follows:

The parameter 'LINE/DEFINITION/SUPPRESSION.' may be given the value "-1." to delete the line, the value "0." to enable drawing of the line, and the value "+1." to temporarily disable drawing of the line. It has the default value "0.". When a line is deleted, 'LINE/NUMBER.' becomes undefined.
The parameter 'LINE/DEFINITION/CHARACTER-WIDTH.' specifies the desired width of each character in the line, stated as a fraction of the smaller dimension of the grid window. The default width is ".015".
The parameter 'LINE/DEFINITION/TEXT.' identifies the character string comprising the text of the label. The default value is a single blank.
The parameter 'LINE/DEFINITION/LENGTH.' specifies the length of the character string. The default value is a "1.".
The parameter 'LINE/DEFINITION/INDEX.' is not normally set by a user program. It is maintained by AUTOGRAPH and specifies the index (in the line buffer) of the next line belonging to the label.

See the section "PARAMETERS" for further information about these parameters. Also see examples "agex05" , "agex07", and "agex13".

Note: As a convenience to the user, an AGSETC call to set 'LINE/DEFINITION/TEXT.' sets both the parameters defining the text of the label ('...TEXT.' and '...LENGTH.') the latter being computed by examining the string. The string must be no longer than the length specified by the value of 'LINE/MAXIMUM.' and, if shorter, it must be followed by the 'LINE/END.' character.

The Label Boxes

Each informational label is considered to lie in one of six "label boxes", as follows:

Box 1 lies to the left of the grid window. It contains all labels which have a basepoint on the left edge of the grid window and a leftward-pointing offset vector.
Box 2 lies to the right of the grid window. It contains all labels which have a basepoint on the right edge of the grid window and a rightward-pointing offset vector.
Box 3 lies below the grid window. It contains all labels which have a basepoint on the bottom edge of the grid window and a downward-pointing offset vector.
Box 4 lies above the grid window. It contains all labels which have a basepoint on the top edge of the grid window and an upward-pointing offset vector.
Box 5 lies in the interior of the grid window. It contains all labels which have a basepoint on some edge of the grid window and an inward-pointing offset vector.
Box 6 covers the entire grid window and contains all of the remaining labels.

Three restrictions must be observed by the user:

No label's basepoint may have coordinates (0.,0.), (0.,1.), (1.,0.), or (1.,1.); these corner points must be avoided.
No portion of any label in boxes 1 through 4 may lie inside the grid window.
No portion of any label in box 5 may lie outside the grid window.

The label-box concept is important in handling overlap problems, which are discussed in the next paragraph.

Background Overlap Problems

The responsibility for avoiding background overlap problems might reasonably have been placed squarely on the shoulders of the user, except for one unpleasant fact: numeric labels are unpredictable critters. Accordingly, AUTOGRAPH accepts a part of the burden.

In attempting to keep the numeric labels on a given axis from overlapping each other, AUTOGRAPH may shrink and/or reorient them. Either or both of these actions may be suppressed by the user by resetting 'AXIS/s/CONTROL.'. If a problem still exists, some of the labels may be omitted - perhaps leaving only every second one, every third one, every fourth one, etc.

Informational labels are positioned by the user along the edges of the grid window as if numeric labels did not exist. AUTOGRAPH takes the following actions in attempting to prevent the informational labels from overlapping the numeric labels on any axis:

Box 1 labels (to the left of the grid window) are moved leftward, box 2 labels (to the right of the grid window) are moved rightward, box 3 labels (below the grid window) are moved downward, box 4 labels (above the grid window) are moved upward, and box 5 labels (inside the grid window) are moved inward. Box 6 labels are not moved.
If, during step 1, a label is shoved outside the graph window by the numeric labels on some axis, those numeric labels may be shrunk and/or re-oriented, as allowed by the user's setting of 'AXIS/s/CONTROL.'.
If one or more of the labels in a given box still lies partly outside the graph window, the labels in that box may be shrunk, depending on the current setting of 'LABEL/CONTROL.'. Each label in the box shrinks toward the end of its offset vector.
If one or more of the labels in boxes 1 through 4 still lies partly outside the graph window, all of the labels in that box may be moved inward, shoving numeric labels ahead of them - onto, and perhaps across, an axis.

The algorithms used to do all of this are not perfect; if pushed too severely, they may fail to produce an esthetically pleasing or even minimally acceptable graph. In such cases, the user must take remedial action.

Note: None of the actions described above modify any of the parameters except 'AXIS/s/NUMERIC/ANGLE/1ST.', which may be negated by subtracting a multiple of "360.". Also, no label is shrunk to less than a readable size.

Dashed-Line Patterns for Curves

The subroutine AGCURV draws curves (one per call). It does this by issuing calls to the routines DASHD, FRSTD, VECTD, and LASTD, in the DASHCHAR package. Each curve may thus be drawn using its own particular dashed-line pattern. One of AGCURV's arguments, called KDSH, specifies the dashed-line pattern to be used for a given curve:

If KDSH is zero, the caller is assumed to have done his own call to DASHD. AGCURV does not call it.
If KDSH is non-zero, AGCURV calls DASHD.
If KDSH is positive, its value (modulo n) specifies one of n "user" patterns, defined by the parameter group named 'DASH.'. See example "agex07".
If KDSH is negative, its absolute value (modulo 26) specifies one of 26 "alphabetic" patterns. The curve is drawn using a solid line which is interrupted periodically by the selected letter of the alphabet. See example "agex08".

The nature of the "user" set of dashed-line patterns is discussed in the next paragraph.

The Parameter Group 'DASH.'

The following parameters all belong to the group 'DASH.':

The parameter 'DASH/SELECTOR.' specifies the type of dashed-line patterns to be used by the routines EZMY and EZMXY (EZY and EZXY always use the first of the "user" patterns). If the value of 'DASH/SELECTOR.' is zero or negative, the alphabetic set of (26) dashed-line patterns will be used; if its value is positive and has magnitude "n", then the first "n" of the "user" patterns will be used. The default value is "1.".
The parameter 'DASH/LENGTH.' specifies the assumed length of character-string dashed-line patterns; it must be set to the proper value prior to any AGSETC call setting one of the "user" dashed-line patterns 'DASH/PATTERN/n.'. The default value is "8.".
The parameter 'DASH/CHARACTER.' specifies the curve length devoted to a character other than a dollar sign or a quote in a character-string dashed-line pattern, stated as a fraction of the smaller side of the grid window. The default value is ".010".
The parameter 'DASH/DOLLAR-QUOTE.' specifies the curve length devoted to a dollar sign (a solid section of the line) or a quote (a gap in the line), stated as a fraction of the smaller side of the grid window. The default value is ".010".
Each of the parameters 'DASH/PATTERN/1.', 'DASH/PATTERN/2.', etc., up to 'DASH/PATTERN/26.' defines one of the dash patterns in the "user" group. Any of the routines AGSETI, AGSETF, or AGSETR may be used to give one of these parameters a positive integral value between 0. and 65535., inclusive, in which case the low-order 16 bits of it are interpreted as a dash pattern; the 0 and 1 bits represent "pen-up" and "pen-down" segments three plotter units long. The routine AGSETC may be used to (in effect) store a character string (of the length specified by 'DASH/LENGTH.') as the value of one of these parameters. In such a character string, a quote represents a "pen-up" segment of the length specified by 'DASH/DOLLAR-QUOTE.', a dollar sign represents a "pen-down" segment of that length, and every other character is simply drawn as a part of the line (with a width specified by 'DASH/CHARACTER.'). The default value of all 26 parameters is "65535.".

See examples "agex07" and "agex08".

Patterns Used by EZY, EZXY, EZMY, and EZMXY

Each of the routines EZY and EZXY, which draw one curve per call, calls AGCURV with KDSH equal to 1, specifying the use of the first of the "user-defined" set of dashed-line patterns (default - a solid line) for the single curve to be drawn.

Each of the routines EZMY and EZMXY, which draw one or more curves per call, calls AGCURV with KDSH equal to ISIGN(I,IDSH), where I is the number of the curve being drawn and IDSH is the integral value of 'DASH/SELECTOR.'. This parameter has the default value "1.", specifying the use of the "user" set of dashed-line patterns (default - solid lines); the value "-1." specifies the use of the "alphabetic" set.

Windowing of Curves

The parameter 'WINDOW.' has the default value "0.". If it is set to a "1." by a user program, curves subsequently drawn by the routine AGCURV are "windowed". This means that only those portions lying inside the grid window are drawn; the effect is as if one were viewing the curve through an actual window.

See the example "agex07".

Use of PWRITX by AUTOGRAPH

Normally, the routine PWRIT is used for all characters drawn by AUTOGRAPH. Actually, a routine AGPWRT is called; the default version of that routine just passes its arguments on to PWRIT. Trying to use PWRITX instead poses some problems. Because "function codes" may be used in a text string passed to PWRITX, the length of the string cannot be taken to match the actual number of characters to be drawn; moreover, PWRITX does not use the same plotter width for each character in a string. Thus, AUTOGRAPH cannot properly predict where on a graph a label drawn by PWRITX lies, which interferes with its handling of overlap problems; also, strings which are positioned relative to an end-point may not be properly aligned.

Nevertheless, there is a way to make AUTOGRAPH use PWRITX: On a Unix system, one simply appends a "-agupwrtx" to the "ncargf77" command. This will cause to be loaded an alternate version of AGPWRT that calls PWRITX. (If "ncargf77" is not being used, one must append to the "f77" command the proper name of the library containing the alternate version of AGPWRT; this name may be obtained from an NCAR Graphics consultant.) When the alternate version of AGPWRT is used, a string which is centered relative to a given position (like the "x-axis label", the "y-axis label", or the "graph label") is drawn directly, in its entirety, by PWRITX, and may therefore contain function codes to get Greek characters, subscripts, superscripts, etc. A string which is positioned relative to one end (which includes all numeric labels) is drawn by passing one character at a time to PWRITX, so that the same plotter width will be used for each; function codes must not be included in such strings. The results, while not as pleasing as one would normally expect from PWRITX, are more than just acceptable.

In my opinion, the "duplex" character set of PWRITX is far superior to the "complex" set. At present, one uses it by incorporating the following code at the beginning of one's program, prior to any call to PWRITX (directly or indirectly):

      COMMON /PUSER/ MODE
       : : :
      MODE = 1

Use of PLOTCHAR by AUTOGRAPH

The "new" character-drawing utility called PLOTCHAR, written in 1988, has supplanted PWRITX. AUTOGRAPH would have to be modified to use PLOTCHAR properly (taking advantage of PLOTCHAR's ability to compute text-extent quantities). This used to be on the list of things to be done, but it was not a trivial task, was never done, and, realistically, will probably never be done. Nevertheless, there is a way to make AUTOGRAPH use PLOTCHAR in a way that works pretty well: Compile this version of the routine AGPWRT along with your program to replace the default version, and, somewhere in your program, put the following declaration:

      COMMON /PSSFLG/ IFLG

Then, if you want AUTOGRAPH to use PLOTCHAR routines to write all labels, set IFLG non-zero; otherwise, set IFLG to zero.

Use of DASHPACK by AUTOGRAPH

It is possible to make AUTOGRAPH use the "new" dash package (written in 1994), called DASHPACK, instead of the old package, called DASHCHAR.

For details, see the example "agdp01".

Varying Intensities, Color, Etc.

Three routines - AGCHAX, AGCHCU, and AGCHIL (the default versions of which do nothing) - are provided solely to be replaced by the user; the replacement versions may change intensities, line widths, colors, line styles, etc., for selected portions of a graph. Each is called just before an object is to be drawn and again just after it has been drawn, with arguments enabling the user version to completely identify what the current situation is and to make the appropriate calls. AGCHAX handles objects which are parts of axes, AGCHCU handles curves, and AGCHIL handles informational labels.

See the descriptions of these routines, in the section "ROUTINES".

Non-Standard Numeric Labels

The routine AGCHNL (the default version of which does nothing) is called just after the character form of a numeric label has been constructed and just before it is to be drawn. The user may supply a version of this routine to transform selected numeric labels in any desired fashion and return them to AUTOGRAPH. This feature may be used to label an axis with the names of the months, Roman numerals, etc.

See the description of the routine AGCHNL, in the section "ROUTINES", and also example "agex10".

Scattergrams and Histograms

Scattergrams, histograms, and other such specialized "graphs" are not directly provided for by AUTOGRAPH. Standard procedure is to suppress the advancing of the frame and the drawing of curves by EZxxx, call EZxxx with the appropriate X and Y data to generate the background, draw the desired objects on that background, and then advance the frame.

See examples "agex11" and "agex12" .

ROUTINES

This section describes all of the AUTOGRAPH routines of interest to the user. With two exceptions, they are subroutines rather than functions.

The subroutines EZY, EZXY, EZMY, and EZMXY provide a quick-and-dirty graph-drawing capability. The appearance of a graph drawn by one of these routines may be changed drastically by changing the values of primary control parameters.

The subroutines ANOTAT and DISPLA are provided principally for historical reasons. Each allows the user to provide new values for certain primary control parameters. These parameters may also be set by calls to lower-level routines.

The subroutines AGSETC, AGSETF, AGSETI, AGSETP, and AGSETR allow the user to set the values of parameters.

The subroutines AGGETC, AGGETF, AGGETI, AGGETP, and AGGETR allow the user to get the current values of parameters.

The subroutine AGSTUP must be called prior to calling AGBACK or AGCURV, both initially and after making any change in the primary control parameters. It examines the primary control parameters for consistency and computes the values of required secondary control parameters.

The subroutine AGBACK is called to draw a background.

The subroutine AGCURV is called to draw a single curve.

The subroutines AGSAVE and AGRSTR are called to save/restore the current state (commonly the default state) of AUTOGRAPH.

The function AGBNCH may be used to obtain the 16-character dash pattern which is equivalent to a specified 16-bit integer dash pattern.

The function AGDSHN may be used to obtain the 16-character name of a particular specified dash-pattern parameter.

The subroutine AGUTOL is called by AUTOGRAPH to do the mapping from the user system to the label system (or vice-versa) along the four axes. The default version may be replaced by the user to obtain a desired mapping.

The subroutines AGCHAX, AGCHCU, and AGCHIL are called by AUTOGRAPH just before and just after drawing a particular element of a graph. The default do-nothing versions may be replaced by a user in order to obtain desired effects (color, different line styles, etc.).

The subroutine AGCHNL is called by AUTOGRAPH just after the character representation of a numeric label has been generated and just before it is to be drawn. The default do-nothing version may be replaced by a user in order to change the numeric labels in a desired way (to get names of months, Roman numerals, etc.).

The subroutine AGPWRT is called by AUTOGRAPH to draw a character string. The default version just calls the plot-package routine PWRIT. This routine may be replaced by a user version which calls PWRITX, PWRITY, or some other character-drawer.

Note: User versions of AGUTOL, AGCHAX, AGCHCU, AGCHIL, AGCHNL, and AGPWRT should not call any other AUTOGRAPH routine. No such call will have a useful effect, and, at worst, an infinite loop may result.

EZY (YDRA,NPTS,GLAB)

Draws, in a manner determined by the current values of the control parameters, a complete graph of a single curve through the points (I,YDRA(I)), for I from 1 to NPTS. The argument GLAB may be used to specify a "graph label", to be placed at the top of the graph.

Usage

If the default values of the parameters are unchanged, calling EZY produces a graph having the following appearance: A "perimeter" background outlines a grid window which is 8/10 the width and 8/10 the height of the plotter frame and positioned slightly above and to the right of center within it. Each edge of the perimeter has short inward-pointing major and minor tick marks, with major tick marks occurring at the ends of each edge. Numeric labels below major tick marks on the bottom edge of the perimeter, increasing in value from left to right, show the linear mapping of values of I onto the horizontal (X) axis of the graph; below them is the label "X". Numeric labels to the left of major tick marks on the left edge of the perimeter, increasing in value from bottom to top, show the linear mapping of values of YDRA(I) onto the vertical (Y) axis of the graph; to the left of them is the label "Y". Above the perimeter is the label specified by "GLAB", if any. The curve itself is drawn as a solid line within the perimeter. A frame advance is done after the graph is drawn.

See example "agex01".

The appearance of a graph drawn by EZY may change greatly in response to parameter changes. See the routines ANOTAT, DISPLA, and AGSETP, below, and the section "PARAMETERS".

Arguments

YDRA (an input array of type REAL, dimensioned at least NPTS) defines the Y coordinates of points on the curve. The current value of 'NULL/1.' (default value "1.E36") may be used in YDRA to signal missing points; curve segments on either side of a missing point are omitted.

NPTS (an input expression of type INTEGER) is the number of curve points defined by the array YDRA.

GLAB (an input expression of type CHARACTER) defines a new "graph label". (If the first character of this expression is "CHAR(0)", no new "graph label" is defined; the current one will continue to be used.) A character string defining a new graph label must either be of the exact length specified by the current value of 'LINE/MAXIMUM.' (default: 40 characters), or shorter; if shorter, it must be terminated by the character defined by the current value of 'LINE/END.' (default: a '$'). The string becomes the new text of line number 100 of the label named 'T'.

EZXY (XDRA,YDRA,NPTS,GLAB)

Draws, in a manner determined by the current values of the control parameters, a complete graph of a single curve through the points (XDRA(I),YDRA(I)), for I from 1 to NPTS. The argument GLAB may be used to specify a "graph label", to be placed at the top of the graph.

Usage

If the default values of the parameters are unchanged, calling EZXY produces a graph having the following appearance: A "perimeter" background outlines a grid window which is 8/10 the width and 8/10 the height of the plotter frame and positioned slightly above and to the right of center within it. Each edge of the perimeter has short inward-pointing major and minor tick marks, with major tick marks occurring at the ends of each edge. Numeric labels below major tick marks on the bottom edge of the perimeter, increasing in value from left to right, show the linear mapping of values of XDRA(I) onto the horizontal (X) axis of the graph; below them is the label "X". Numeric labels to the left of major tick marks on the left edge of the perimeter, increasing in value from bottom to top, show the linear mapping of values of YDRA(I) onto the vertical (Y) axis of the graph; to the left of them is the label "Y". Above the perimeter is the label specified by "GLAB", if any. The curve itself is drawn as a solid line within the perimeter. A frame advance is done after the graph is drawn.

See example "agex02".

The appearance of a graph drawn by EZXY may change greatly in response to parameter changes. See the routines ANOTAT, DISPLA, and AGSETP, below, and the section "PARAMETERS".

Arguments

XDRA (an input array of type REAL, dimensioned NPTS) defines the X coordinates of points on the curve.

YDRA (an input array of type REAL, dimensioned NPTS) defines the Y coordinates of points on the curve.

The points on the curve have coordinates (XDRA(I),YDRA(I)), for I from 1 to NPTS. The current value of 'NULL/1.' (default value "1.E36") may be used to signal missing data in these arrays. If either coordinate of a point is missing, the point is considered to be missing; curve segments on either side of a missing point are not drawn. Note: Because all non-missing coordinates are used in figuring the minimum and maximum user values along a given axis, it is safest to mark both coordinates as "missing".

NPTS (an input expression of type INTEGER) is the number of curve points defined by the arrays XDRA and YDRA.

EZMY (YDRA,IDXY,MANY,NPTS,GLAB)

Draws, in a manner determined by the current values of the control parameters, a complete graph of one or more curves, each defined by a set of points (I,YDRA(I,J)) (or (I,YDRA(J,I)), depending on the current value of 'ROW.'), for I from 1 to NPTS. The curve number J runs from 1 to MANY. The argument GLAB may be used to specify a "graph label", to be placed at the top of the graph.

Usage

If the default values of the parameters are unchanged, calling EZMY produces a graph having the following appearance: A "perimeter" background outlines a grid window which is 8/10 the width and 8/10 the height of the plotter frame and positioned slightly above and to the right of center within it. Each edge of the perimeter has short inward-pointing major and minor tick marks, with major tick marks occurring at the ends of each edge. Numeric labels below major tick marks on the bottom edge of the perimeter, increasing in value from left to right, show the linear mapping of values of I onto the horizontal (X) axis of the graph; below them is the label "X". Numeric labels to the left of major tick marks on the left edge of the perimeter, increasing in value from bottom to top, show the linear mapping of values of YDRA(I,J) onto the vertical (Y) axis of the graph; to the left of them is the label "Y". Above the perimeter is the label specified by "GLAB", if any. The curves themselves are drawn as solid lines within the perimeter. A frame advance is done after the graph is drawn.

See example "agex03".

The appearance of a graph drawn by EZMY may change greatly in response to parameter changes. See the routines ANOTAT, DISPLA, and AGSETP, below, and the section "PARAMETERS".

Arguments

YDRA (an input array of type REAL, dimensioned IDXY x MANY or IDXY x NPTS, depending on the current value of 'ROW.') defines curve-point Y coordinates. The current value of 'NULL/1.' (default value "1.E36") may be used in YDRA to signal missing points; curve segments on either side of a missing point are omitted.

If 'ROW.' is positive (the default), the first subscript of YDRA is a point number and the second is a curve number.
If 'ROW.' is negative, the order of the subscripts is reversed ("row-wise", as opposed to "column-wise", storage); the first subscript is a curve number and the second is a point number.

IDXY (an input expression of type INTEGER) defines the first dimension of the array YDRA, which is required by EZMY in order to index the array properly.

If 'ROW.' is positive (the default), IDXY must be greater than or equal to NPTS.
If 'ROW.' is negative, IDXY must be greater than or equal to MANY.

MANY (an input expression of type INTEGER) is the number of curves to be drawn by EZMY.

NPTS (an input expression of type INTEGER) is the number of points defining each curve to be drawn by EZMY.

EZMXY (XDRA,YDRA,IDXY,MANY,NPTS,GLAB)

Draws, in a manner determined by the current values of the control parameters, a complete graph of one or more curves, each defined by a set of points (XDRA(I),YDRA(I,J)) (or (XDRA(I),YDRA(J,I)) or (XDRA(I,J),YDRA(I,J)) or (XDRA(J,I),YDRA(J,I)), depending on the current value of 'ROW.'), for I from 1 to NPTS. The curve number J runs from 1 to MANY. The argument GLAB may be used to specify a "graph label", to be placed at the top of the graph.

Usage

If the default values of the parameters are unchanged, calling EZMXY produces a graph having the following appearance: A perimeter background outlines a grid window which is 8/10 the width and 8/10 the height of the plotter frame and positioned slightly above and to the right of center within it. Each edge of the perimeter has short inward-pointing major and minor tick marks, with major tick marks occurring at the ends of each edge. Numeric labels below major tick marks on the bottom edge of the perimeter, increasing in value from left to right, show the linear mapping of values of XDRA(I) onto the horizontal (X) axis of the graph; below them is the label "X". Numeric labels to the left of major tick marks on the left edge of the perimeter, increasing in value from bottom to top, show the linear mapping of values of YDRA(I,J) onto the vertical (Y) axis of the graph; to the left of them is the label "Y". Above the perimeter is the label specified by "GLAB", if any. The curves themselves are drawn as solid lines within the perimeter. A frame advance is done after the graph is drawn.

See example "agex04".

The appearance of a graph drawn by EZMXY may change greatly in response to parameter changes. See the routines ANOTAT, DISPLA, and AGSETP, below, and the section "PARAMETERS".

Arguments

XDRA (an input array of type REAL, dimensioned NPTS or IDXY x MANY or IDXY x NPTS, depending on the current value of 'ROW.') contains curve-point X coordinates. The current value of 'NULL/1.' (default value "1.E36") may be used in XDRA to signal missing points; curve segments on either side of a missing point are not drawn. Note: Because all non-missing coordinates are used in figuring the minimum and maximum user values along a given axis, it is safest to mark both coordinates as "missing".

If 'ROW.' has the absolute value "1." (the default), XDRA is singly-dimensioned. It is subscripted by point number.
If 'ROW.' has the absolute value "2." or greater, XDRA is doubly-dimensioned. It is subscripted by point number and curve number, in that order if 'ROW.' is positive (the default), and in the reverse order if 'ROW.' is negative.

YDRA (an input array of type REAL, dimensioned IDXY x MANY or IDXY x NPTS, depending on the current value of 'ROW.') contains curve-point Y coordinates. The current value of 'NULL/1.' (default value "1.E36") may be used in YDRA to signal missing points; curve segments on either side of a missing point are not drawn. Note: Because all non-missing coordinates are used in figuring the minimum and maximum user values along a given axis, it is safest to mark both coordinates as "missing".

If 'ROW.' is positive (the default), YDRA is subscripted by point number and curve number, in that order.
If 'ROW.' is negative, YDRA is subscripted by curve number and point number, in that order.

IDXY (an input expression of type INTEGER) is the first dimension of the arrays XDRA (if it is doubly-dimensioned) and YDRA (unconditionally), required by EZMXY in order to index these arrays properly.

If 'ROW.' is positive (the default), IDXY must be greater than or equal to NPTS.
If 'ROW.' is negative, IDXY must be greater than or equal to MANY.

MANY (an input expression of type INTEGER) is the number of curves to be drawn by EZMXY.

NPTS (an input expression of type INTEGER) is the number of points defining each curve to be drawn by EZMXY.

ANOTAT (XLAB,YLAB,LBAC,LSET,NDSH,DSHC)

Changes the values of certain primary control parameters, purportedly having to do with "annotation" of a graph.

Usage

The subroutine ANOTAT is provided principally for historical reasons. Each of the parameters referenced by its argument list can be set individually by means of the routines AGSETC, AGSETF, AGSETP, and/or AGSETR. In fact, ANOTAT is implemented using calls to these routines.

See example "agex08".

Arguments

XLAB (an input expression of type CHARACTER) defines a new "x-axis label". (If the first character of this expression is "CHAR(0)", no new "x-axis label" is defined; the current one will continue to be used.) A character string defining a new X-axis label must either be of the exact length specified by the current value of 'LINE/MAXIMUM.' (default: 40 characters), or shorter; if shorter, it must be terminated by the character defined by the current value of 'LINE/END.' (default: a '$'). The string becomes the new text of line number -100 of the label 'B'.

YLAB (an input expression of type CHARACTER) defines a new "y-axis label". (If the first character of this expression is "CHAR(0)", no new "y-axis label" is defined; the current one will continue to be used.) A character string defining a new Y-axis label must either be of the exact length specified by the current value of 'LINE/MAXIMUM.' (default: 40 characters), or shorter; if shorter, it must be terminated by the character defined by the current value of 'LINE/END.' (default: a '$'). The string becomes the new text of line number 100 of the label 'L'.

LBAC (an input expression of type INTEGER), if non-zero, must have the integer value 1, 2, 3, or 4, the real equivalent of which is to become the new value of 'BACKGROUND.'. (If LBAC is zero, no change is to be made in the current value.) The value "1" specifies a perimeter background, the value "2" a grid background, the value "3" a half-axis background, and the value "4" no background at all.

See the discussion of 'BACKGROUND.', in the section "PARAMETERS".

LSET (an input expression of type INTEGER), if non-zero, must have the absolute value 1, 2, 3, or 4, the real equivalent of which is to be stored (by means of a call to AGSETI) as the new value of 'SET.'. If LSET is zero, no change is to be made in the current value of 'SET.'.

See the discussion of 'SET.', in the section "PARAMETERS".

NDSH (an input expression of type INTEGER), if zero, specifies that no change is to be made in the parameters which specify the dashed-line patterns to be used for curves.

If NDSH is non-zero, it specifies an integer value whose real equivalent is to be stored as the new value of 'DASH/SELECTOR.' (which has the default value "1.").
If NDSH is negative, 'DASH/SELECTOR.' is set negative, forcing EZMY and EZMXY to use internally-defined "alphabetic" patterns for the MANY curves drawn ("A" for the first, "B" for the second, . . ., "Z" for the 26th, "A" for the 27th, etc.). The routines EZY and EZXY are unaffected.
If NDSH is greater than zero, it must be less than or equal to 26, and the next argument, DSHC, must contain NDSH dashed-line patterns comprising the new "user" set of patterns. The fact that 'DASH/SELECTOR.' is set positive forces EZMY and EZMXY to use this set of patterns. (The routines EZY and EZXY always use the first pattern in this set.) The contents of the array DSHC are copied to storage local to AUTOGRAPH and pointers to them are installed as the values of 'DASH/PATTERNS/1.', '.../2.', etc.

See the discussion of 'DASH.', in the section "PARAMETERS".

DSHC (an input array of type CHARACTER, dimensioned NDSH) is meaningful only when NDSH is greater than zero. In this case, it must be an array of NDSH character strings, each of the length specified by the current value of 'DASH/LENGTH.'. Each character string represents a dashed-line pattern; dollar signs mean "pen down", quotes mean "pen up", and other characters mean "draw me".

See the discussion of 'DASH.', in the section "PARAMETERS".

DISPLA (LFRA,LROW,LTYP)

Changes the values of certain primary control parameters purportedly having to do with the "display" of a graph.

Usage

The subroutine DISPLA is provided principally for historical reasons. Each of the parameters referenced by its argument list can be set individually by means of the routines AGSETP and/or AGSETI. In fact, DISPLA is implemented using calls to these routines.

See the example "agex13".

Arguments

LFRA (an input expression of type INTEGER), if non-zero, must have an integer value, the real equivalent of which is to become the new value of 'FRAME.'. If LFRA is zero, no change is to be made in the current value of 'FRAME.'.

The default value of 'FRAME.' is "1.", specifying that each of the routines EZY, EZXY, EZMY, and EZMXY is to do a frame advance after drawing a graph.
The value "2." specifies no frame advance.
The value "3." specifies a frame advance before drawing a graph.

LROW (an input expression of type INTEGER), if non-zero, must have an integer value, the real equivalent of which is to become the new value of 'ROW.'. If LROW is zero, no change is to be made in the current value of 'ROW.'. This parameter affects the way in which the routines EZMY and EZMXY interpret the arguments XDRA and YDRA, as follows:

If 'ROW.' is positive, the first subscript of YDRA is a point number and the second subscript is a curve number. If 'ROW.' is negative, the order of the subscripts is reversed (row-wise, rather than column-wise, storage).
If the absolute value of 'ROW.' is "1.", XDRA is singly-subscripted; its subscript is a point number. If the absolute value of 'ROW.' is "2." or greater, XDRA is doubly-subscripted; the order of the subscripts is the same as for YDRA.

The default value of 'ROW.' is "1.", specifying that XDRA is singly-subscripted by point number and that YDRA is doubly-subscripted by point number and curve number, in that order.

LTYP (an input expression of type INTEGER), if non-zero, is an integer specifying new values for 'X/LOGARITHMIC.' and 'Y/LOGARITHMIC.'. If LTYP is zero, no change is to be made in the current values.

The parameter 'X/LOGARITHMIC.' has the default value "0.", specifying a linear mapping of user X coordinates onto the horizontal axis of the grid window; it may be given either of the two values "-1." or "+1." to specify a logarithmic mapping. The value "-1." protects it from being reset as a side effect of setting 'SET.'. DISPLA generates the value "0." or "-1.".
The parameter 'Y/LOGARITHMIC.' is defined similarly and affects the mapping of user Y coordinates onto the vertical axis of the grid window.

A non-zero LTYP resets these values, as follows:

LTYP 'X/LOGARITHMIC.' 'Y/LOGARITHMIC.'
1 linear linear
2 linear logarithmic
3 logarithmic linear
4 logarithmic logarithmic

LTYP	'X/LOGARITHMIC.'	'Y/LOGARITHMIC.'
1	linear	linear
2	linear	logarithmic
3	logarithmic	linear
4	logarithmic	logarithmic

AGSETP (TPGN,FURA,LURA)

Allows a user program to reset the values of a group of parameters containing one or more elements.

Usage

The subroutine AGSETP is called with a character string identifying a group of parameters (possibly a single parameter), an array containing new values of those parameters, and the length of the array, as arguments. It transfers the new values into the appropriate locations in the labeled common block AGCONP, thus modifying the effect of subsequent calls to other AUTOGRAPH routines.

If a single parameter is being set, one of the routines AGSETC, AGSETF, AGSETI, or AGSETR (which see, below) may be used instead.

When certain parameters are set individually, AGSETP takes further "special" action. For example, if 'BACKGROUND.' is set, thereby requesting one of the standard types of backgrounds, AGSETP changes a number of other parameters in order to achieve the desired effect. The parameters which imply such special action are as follows:

      'SET.'
      'BACKGROUND.'
      'NULL/1.' and 'NULL/2.'
      'LABEL/CONTROL.'
      'LABEL/NAME.'
      'LABEL/DEFINITION/SUPPRESSION.'
      'LINE/NUMBER.'
      'LINE/DEFINITION/SUPPRESSION.'
      'LINE/DEFINITION/TEXT.'

See the section "PARAMETERS" for descriptions of the parameters whose values may be set. Special actions, if any, which accompany the setting of a parameter are detailed there.

Arguments

TPGN (an input expression of type CHARACTER) is a character string of the form 'k₁/k₂/ . . . k_n.', where each of the k_i's is a keyword. The keyword k₁ specifies a group of parameters, k₂ a subgroup of that group, k₃ a subgroup of that subgroup, etc. The whole string is the name of some group of parameters the user wishes to set.

For example, 'AXIS.' is the name of a 92-word group of parameters describing the four axes, 'AXIS/RIGHT.' is the name of a 23-word subgroup describing the right Y axis,

      'AXIS/RIGHT/INTERSECTION.'

is the name of a 2-word further subgroup describing the intersection of the right Y axis with the bottom of the grid window, and

      'AXIS/RIGHT/INTERSECTION/USER.'

is the name of a single parameter specifying the point of intersection of the right Y axis with the bottom of the grid window as an X coordinate in the user coordinate system.

Obviously, these names can sometimes become rather long. There are various ways in which they may be shortened. First, since the fifth and following characters of each keyword are ignored, they may be omitted; this would shorten

      'AXIS/RIGHT/INTERSECTION/USER.'

      'AXIS/RIGH/INTE/USER.'

Even fewer characters may be used, as long as no ambiguity of interpretation arises. To be completely safe, use at least the first three characters of the group keyword and at least the first two characters of each subgroup keyword; this would shorten the example above to 'AXI/RI/IN/US.'. Moreover, certain group and subgroup keywords may be omitted entirely; for example, 'AXI/RI/IN/US.' may be shortened to 'RI/IN/US.'. Keywords which may be entirely omitted are enclosed in brackets in the headings in the section "PARAMETERS".

Names may also be lengthened in various ways in order to improve their readability. Blanks may be used as desired on either side of a keyword. Any sequence of characters not including a slash or a period may be inserted after a keyword, separated from it by at least one blank. For example, the name

      'DASH PATTERN / CHARACTER WIDTH .'

is equivalent to, and considerably more meaningful than,

      'DAS/CH.' (or even 'DASH/CHARACTER.')

A complete list of the parameters may be found in the section "PARAMETERS", below.

FURA (an input array of type REAL, dimensioned LURA) contains new values for the parameters in the group specified by TPGN, in the same order as they appear in the group. All parameters have real values (because of a portability problem which arose in implementing the routines AGSETF and AGSETR). Those which represent intrinsically integral quantities have a value of the form "FLOAT(n)", where "n" is the integral quantity being represented. Some parameters intrinsically take on character-string values; the real quantity stored as the value of such a parameter is typically an identifier allowing for later retrieval of the character string from a character storage area inside AUTOGRAPH. The routines AGSETC and AGGETC may be used to set/get the character-string values of such parameters.

LURA (an input expression of type INTEGER) is the length of FURA (the number of real elements in it). Its value may be less than, equal to, or greater than, the length of the parameter group specified by TPGN. The number of values transferred from FURA is the minimum of the two (but not less than one). This means that if, for example, you only wish to set the first two parameters of a 100-parameter group, you may do so by using LURA = 2.

AGSETF (TPGN,FUSR) or AGSETR (TPGN,FUSR)

Allows a user program to store a real number as the value of a single parameter.

Usage

Either of these subroutines transfers the value of FUSR to a local array FURA, dimensioned 1, and executes the statement

      CALL AGSETP (TPGN,FURA,1)

See the description of AGSETP, above. The "special actions" described there may result from a call to AGSETF or AGSETR.

Arguments

TPGN (an input expression of type CHARACTER) is an parameter identifier, as described for AGSETP, above. If a group of more than one parameter is specified, only the first element of that group will be affected by the call.

FUSR (an input expression of type REAL) is the value to be given to the parameter specified by TPGN.

AGSETI (TPGN,IUSR)

Allows a user program to store the real equivalent of an integer as the value of a single parameter.

Usage

This subroutine stores the value FLOAT(IUSR) in a local array FURA, dimensioned 1, and then executes the statement

      CALL AGSETP (TPGN,FURA,1)

See the description of AGSETP, above. The "special actions" described there may result from a call to AGSETI.

Arguments

TPGN (an input expression of type CHARACTER) is a parameter identifier, as described for AGSETP, above. If a group of more than one parameter is specified, only the first element of that group will be affected by the call.

IUSR (an input expression of type INTEGER) is the value to be given to the parameter specified by TPGN.

AGSETC (TPGN,CUSR)

Allows a user program to (in effect) store a character string as the value of a specified single parameter.

Usage

This subroutine stores the character string CUSR in an internal string storage space, generates a real identifier allowing for later retrieval of the character string, stores that identifier in a local array FURA, dimensioned 1, and then executes the statement

      CALL AGSETP (TPGN,FURA,1)

See the description of AGSETP, above. The "special actions" described there may result from a call to AGSETC.

Arguments

TPGN (an input expression of type CHARACTER) is a parameter identifier, as described for AGSETP, above. The specified parameter must be one of those which intrinsically have values of type character: 'LINE/END.', 'LABEL/NAME.', 'LINE/TEXT.', or 'DASH/PATTERN/n.'

CUSR (an input expression of type CHARACTER) is the desired character string.

If 'LINE/END.' is being set, only the first character of CUSR will be used.
If 'LABEL/NAME.' is being set, the length of the string CUSR will be taken to be "MAX(1,LEN(CUSR))".
If the text of a label is being set, CUSR must either be of the exact length specified by 'LINE/MAXIMUM.' (40 characters, by default) or shorter; if shorter, it must be terminated by the character defined by 'LINE/END.' (default: a '$').
If a dash pattern is being set, the length of CUSR will be taken to be the minimum of "LEN(CUSR)" and the value specified by 'DASH/LENGTH.'.

AGGETP (TPGN,FURA,LURA)

Allows a user program to get the values of a group of parameters containing one or more elements.

Usage

The subroutine AGGETP is called with a character string identifying a group of parameters (possibly a single parameter), an array to receive the values of those parameters, and the length of the array, as arguments. It transfers values from the appropriate locations in the labeled common block AGCONP to the user array.

If a single parameter is being retrieved, one of the routines AGGETC, AGGETF, AGGETI, or AGGETR (which see, below) may be used instead. No "special" action is implied for any single parameter (as is the case for AGSETP).

See the section "PARAMETERS" for descriptions of parameters whose values may be retrieved.

Arguments

See the AGSETP argument TPGN, above, for an example and additional comments.

FURA (an output array of type REAL, dimensioned LURA) is the user array into which the real values of the parameters in the group specified by TPGN are to be transferred, in the same order as they appear in the group.

See the AGSETP argument FURA, above, for additional comments.

LURA (an input expression of type INTEGER) is the length of FURA. Its value may be less than, equal to, or greater than, the length of the group specified by TPGN. The number of values transferred into FURA is the minimum of the two (but not less than one). You may, for example, get the first two parameters of a 100-parameter group by using LURA = 2.

AGGETF (TPGN,FUSR) or AGGETR (TPGN,FUSR)

Allows a user program to retrieve the real value of a single parameter.

Usage

Either of these subroutines executes the statement

      CALL AGGETP (TPGN,FURA,1)

where FURA is a local array, dimensioned 1, and then sets FUSR equal to FURA(1).

See the description of AGGETP, above.

Arguments

TPGN (an input expression of type CHARACTER) is a parameter identifier, as described for AGGETP, above. If a group of more than one parameter is specified, only the first element of that group will be retrieved by the call.

FUSR (an output variable of type REAL) receives the real value of the parameter specified by TPGN.

AGGETI (TPGN,IUSR)

Allows a user program to retrieve the integer equivalent of the real value of a single parameter.

Usage

This subroutine executes the statement

      CALL AGGETP (TPGN,FURA,1)

where FURA is a local array, dimensioned 1, and then sets IUSR equal to IFIX(FURA(1)).

See the description of AGGETP, above.

Arguments

IUSR (an output variable of type INTEGER) receives the integer equivalent of the real value of the parameter specified by TPGN.

AGGETC (TPGN,CUSR)

Allows a user program to retrieve (in effect) the character-string values of certain single parameters.

Usage

This subroutine executes the statement

      CALL AGGETP (TPGN,FURA,1)

where FURA is a local array, dimensioned 1. It then retrieves, from AUTOGRAPH's character storage space, the character string identified by FURA(1), and returns that string as the value of CUSR.

See the description of AGGETP, above.

Arguments

TPGN (an input expression of type CHARACTER) is a parameter identifier, as described for AGGETP, above. The specified parameter must be one of those which intrinsically have values of type character: 'LINE/END.', 'LABEL/NAME.', 'LINE/TEXT.', or 'DASH/PATTERN/n.'

CUSR (an output variable of type CHARACTER) receives the desired character string. If CUSR is too short, only the beginning of the string will be put in it. If CUSR is too long, it will be padded with blanks on the end.

AGSTUP (XDRA,NVIX,IIVX,NEVX,IIEX, . . . )

(The remaining arguments are YDRA, NVIY, IIVY, NEVY, and IIEY.) Performs "set-up" tasks required before AGBACK and AGCURV may be called. Basically, AGSTUP examines the current values of the primary control parameters for errors and computes from them and from its arguments the values of secondary control parameters. The primary and secondary control parameters together determine how the routines AGBACK and AGCURV will behave.

Usage

The subroutine AGSTUP should be called once per graph, just prior to the sequence of calls to AGBACK and/or AGCURV which actually draws the graph.

Note that each of the routines EZY, EZXY, EZMY, and EZMXY unconditionally executes a call to AGSTUP (via a routine called AGEZSU) before calling AGBACK and/or AGCURV.

An appropriate call to the plot-package routine SET is executed by AGSTUP. This is important; it allows the user to position things on the graph using X/Y coordinates that are commensurate with his/her data.

Arguments

The first five arguments of AGSTUP are meaningful only if at least one of 'X/MINIMUM.' and 'X/MAXIMUM.' has the value "null 1" or "null 2", specifying that AUTOGRAPH is to determine for itself the minimum and/or maximum X coordinate in the user's data. Similarly, the second five arguments are meaningful only if at least one of 'Y/MINIMUM.' and 'Y/MAXIMUM.' has the value "null 1" or "null 2".

XDRA (an input array of type REAL, dimensioned as implied by the next four arguments) contains user X coordinates.

NVIX (an input expression of type INTEGER) is the number of "vectors" of data from XDRA to be considered in computing the minimum and/or maximum X values.

IIVX (an input expression of type INTEGER) is the index increment between two "vectors" in XDRA. The 1st element of the first vector is XDRA(1), the 1st element of the second vector is XDRA(1+IIVX), the 1st element of the third vector is XDRA(1+IIVX*2), etc.

NEVX (an input expression of type INTEGER) is the number of elements of each vector in XDRA to be considered in computing the minimum and/or maximum X values.

IIEX (an input expression of type INTEGER) is the index increment between two consecutive elements of a vector in XDRA. The second element of the 1st vector is XDRA (1+IIEX), the third element of the 1st vector is XDRA(1+IIEX*2), etc. If IIEX has the value 0, the contents of XDRA are ignored completely; the minimum and maximum X values are considered to be "1." and FLOAT(NEVX), respectively.

YDRA, NVIY, IIVY, NEVY, and IIEY are used similarly, but define the user Y coordinates.

Some examples:

X array Data to use XDRA NVIX IIVX NEVX IIEX
X(100) all data X(1) 1 - 100 1
( X(I), I = 1,99,2 ) X(1) 1 - 50 2
( X(I), I = 51,99,2 ) X(51) 1 - 25 2
X(10,10) all data X(1,1) 10 10 10 1
X(1,1) 1 - 100 1
( ( X(I,J), I = 1,10 ), J = 1,6 ) X(1,1) 6 10 10 1
X(1,1) 10 1 6 10
X(1,1) 1 - 60 1
( ( X(I,J), I = 3,7 ), J = 3,9 ) X(3,3) 7 10 5 1
X(3,3) 5 1 7 10
( ( X(I,J), I = 3,7,4 ), J = 3,9,3 ) X(3,3) 3 30 2 4
none 1., 2., . . ., 62. - - - 62 0

X array	Data to use	XDRA	NVIX	IIVX	NEVX	IIEX
X(100)	all data	X(1)	1	-	100	1
	( X(I), I = 1,99,2 )	X(1)	1	-	50	2
	( X(I), I = 51,99,2 )	X(51)	1	-	25	2
X(10,10)	all data	X(1,1)	10	10	10	1
		X(1,1)	1	-	100	1
	( ( X(I,J), I = 1,10 ), J = 1,6 )	X(1,1)	6	10	10	1
		X(1,1)	10	1	6	10
		X(1,1)	1	-	60	1
	( ( X(I,J), I = 3,7 ), J = 3,9 )	X(3,3)	7	10	5	1
		X(3,3)	5	1	7	10
	( ( X(I,J), I = 3,7,4 ), J = 3,9,3 )	X(3,3)	3	30	2	4
none	1., 2., . . ., 62.	-	-	-	62	0

Note: The character "-" is used above to indicate an argument which is ignored and may be given a dummy value.

Normally, the X and Y coordinate data tendered to AGSTUP are the same data which will later be used to draw curves. However, this need not be the case. For example, one could call AGSTUP with a two-word XDRA (setting NVIX=1, IIVX=1, NEVX=2, and IIEX=1) containing a desired minimum and maximum to be used, disregarding the real data.

If 'INVERT.' is given the value "1." (in place of its default value "0."), AGSTUP will behave as if its first five arguments had been interchanged with its last five, so that X-coordinate values refer to vertical distances, and Y-coordinate values to horizontal distances, on the graph. This parameter affects AGCURV in a similar manner, thus allowing one to plot "X as a function of Y".

AGBACK

Draws the background specified by the current values of the control parameters - the primary parameters with default values or with values supplied by the user, and the secondary parameters with values computed by AGSTUP.

Usage

Just call it. See the section "PARAMETERS" for descriptions of the parameters which affect the appearance of a background drawn by AGBACK. See also the description of AGSTUP, above.

An appropriate call to the plot-package routine SET is executed by AGBACK. This is the same call that was done by AGSTUP; it is re-executed in case the user has done his/her own call to SET in the interim.

Arguments

None.

AGCURV (XVEC,IIEX,YVEC,IIEY,NEXY,KDSH)

Draws a curve in a manner specified by the current values of the control parameters - the primary parameters with default values or with values supplied by the user, and the secondary parameters with values computed by AGSTUP.

Usage

The subroutine AGCURV, given the X and Y coordinates of a set of data points, draws the curve defined by those points, using a dashed-line pattern selected by the final argument.

See the section "PARAMETERS" for a description of the parameters which affect the behavior of AGCURV. One parameter of particular interest is 'WINDOW.', which has the default value "0.". If 'WINDOW.' is given the value "1.", any portion of a curve which lies outside the grid window is omitted. No distortion of any curve segment results; the effect is exactly as if the curve were viewed through a window. There is an additional advantage in setting 'WINDOW.' to "1.": if either the X coordinates, or the Y coordinates, or both, are mapped logarithmically into the grid window and zero or negative values occur in the data, AGCURV treats those values as missing-point signals, rather than bombing with an ALOG10 error.

Arguments

XVEC (a singly-subscripted input array of type REAL), when IIEX is non-zero, contains NEXY X-coordinate data - curve point 1 has X coordinate XVEC(1), curve point 2 has X coordinate XVEC(1+IIEX), curve point 3 has X coordinate XVEC(1+IIEX*2), etc. When IIEX is zero, the array XVEC is ignored - curve point 1 has X coordinate "1.", curve point 2 has X coordinate "2.", etc.

If the value of any X coordinate matches the current value of 'NULL/1.' (default - "1.E36"), the corresponding point is considered to be missing - curve segments on either side of that point are not drawn.

IIEX (an input expression of type INTEGER), if non-zero, is the index increment between one X coordinate in XVEC and the next. If IIEX is zero, the array XVEC is ignored, as described above.

YVEC (a singly-subscripted input array of type REAL) is just like XVEC, but provides Y coordinate data.

IIEY (an input expression of type INTEGER) is just like IIEX, but describes the use (or non-use) of YVEC.

NEXY (an input expression of type INTEGER) is the number of curve points - the number of X/Y coordinate pairs to be used.

Note: If 'INVERT.' is given the value "1." (in place of its default value "0."), AGCURV will behave as if the arguments XVEC and IIEX had been interchanged with the arguments YVEC and IIEY, so that X-coordinate values refer to vertical distances, and Y-coordinate values to horizontal distances, on the graph. This parameter affects AGSTUP in a similar manner, thus allowing one to plot "X as a function of Y".

KDSH (an input expression of type INTEGER) specifies the dashed-line pattern to be used in drawing the curve. (Since the routines DASHD, FRSTD, VECTD, and LASTD, in the package DASHCHAR, are used to draw the curve, it may have its own particular dashed-line pattern.)

If KDSH is zero, the user is assumed to have done his own call to DASHD; AGCURV will do no such call.
If KDSH is non-zero and negative, the function MOD(-KDSH-1,26)+1 determines which of 26 "alphabetic" patterns is to be used; each of these generates a solid line interrupted by one of the letters of the alphabet. The value 1 implies that an "A" will be used, the value 2 that a "B" will be used, . . . the value 27 that an "A" will be used again, etc.
If KDSH is non-zero and positive, the function MOD(KDSH-1,n)+1 determines which of n "user" patterns is to be used; these n patterns are defined by the parameters in the group named 'DASH.' - the default values specify one solid-line pattern.

Note: The routines EZY and EZXY, which draw one curve per call, always call AGCURV with KDSH = 1. The routines EZMY and EZMXY, which draw one or more curves per call, call AGCURV with KDSH = ISIGN(p,q), where p is the number of the curve being drawn (p is between 1 and MANY, inclusive) and q is the current integral value of 'DASH/SELECTOR.'.

AGSAVE (IFNO)

Saves the current state of AUTOGRAPH for later restoration by AGRSTR.

Usage

Calling AGSAVE saves the current state of AUTOGRAPH (frequently the default state) by writing, on the unit specified by IFNO, the current values of all the parameters and the contents of the character storage space referenced by certain of those parameters.

Arguments

IFNO (an input expression of type INTEGER) is the number of a unit to which a single unformatted record is to be written. It is the user's responsibility to position this unit. AGSAVE does not rewind it, either before or after writing the record.

AGRSTR (IFNO)

Restores a saved state of AUTOGRAPH.

Usage

Calling AGRSTR restores AUTOGRAPH to a previously saved state (frequently the default state) by reading, from the unit specified by IFNO, values of all the parameters and the contents of the character storage space referenced by certain of those parameters.

Arguments

IFNO (an input expression of type INTEGER) is the number of a unit from which a single unformatted record is to be read. It is the user's responsibility to position this unit. AGRSTR does not rewind it, either before or after reading the record.

AGBNCH (IDSH)

Provides an easy way to convert binary dash patterns into character dash patterns.

Usage

AGBNCH is a function, of type CHARACTER*16, and must be declared as such in a user program referencing it, by including the statement:

      CHARACTER*16 AGBNCH

The value of AGBNCH (IDSH), where IDSH is an integer in the range 0 to 65535 (2¹⁶-1) representing a 16-bit binary dash pattern, is the equivalent character dash pattern.

Arguments

IDSH (an input expression of type INTEGER) is between 0 and 65535, inclusive.

AGDSHN (IDSH)

Provides an easy way to generate the names of parameters in the group 'DASH/PATTERN.', for use in calls to AGSETC and AGGETC.

Usage

AGDSHN is a function, of type CHARACTER*16, and must be declared as such in a user program referencing it, by including the statement:

      CHARACTER*16 AGDSHN

The value of AGDSHN (IDSH), where IDSH is an integer "n" in the range 1 to 26, is the name of the nth dash-pattern parameter - that is to say, it is the character string 'DASH/PATTERN/n.'.

Arguments

IDSH (an input expression of type INTEGER) is between 1 and 26, inclusive.

AGUTOL (IAXS,FUNS,IDMA,VINP,VOTP)

Provides a way for the user to change the user-system-to-label-system mapping for one or more of the four axes.

Usage

This ro

Autograph, A Package of Routines to Draw X/Y Plots

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