# Example 1 - interpolated function, derivative and integral

```#include <stdio.h>
#include <stdio.h>
#include <ncarg/ncargC.h>
#include <ncarg/gks.h>
#include <ncarg/ngmath.h>

void c_bkgft1(float, char *, float, float);
void c_drwft1(int, float [], float [], int, float [], float [],
float [], float []);

/*
*  Example of curv1, curv2, curvd, curvi.
*/

#define IDIM  11
#define IOUT 201

#define IWTYPE 1
#define WKID   1

main()
{
float x[] = { 0.00,   2.00,   5.00,   8.00,  10.00,  13.00,
15.00,  18.00,  21.00,  23.00,  30.00};
float y[] = { 1.00,   0.81,   0.00,  -0.81,  -1.00,  -0.84,
-0.56,   0.04,   0.73,   1.18,   2.00};
float xinc, xo[IOUT], yo[IOUT], yd[IOUT], yi[IOUT];
int   i;

/*
*  Create the output X coordinate array.
*/
xinc =  30./(IOUT-1);
for (i = 0; i < IOUT; i++) {
xo[i] = xinc * i;
}

/*
*  Require that the derivatives of the interpolated curve are
*  zero at the end points.
*/
c_ftseti("sf1",   0);
c_ftsetr("sl1", 0.0);
c_ftsetr("sln", 0.0);

/*
*  Calculate the interpolated values, the derivative, and the integral.
*/
c_ftcurv(IDIM, x, y, IOUT, xo, yo);
c_ftcurvd(IDIM, x, y, IOUT, xo, yd);
for (i = 0; i < IOUT; i++) {
c_ftcurvi(0., xo[i], IDIM, x, y, yi+i);
}

/*
*  Draw plot.
*/
c_drwft1(IDIM,x,y,IOUT,xo,yo,yd,yi);

}

void c_drwft1(int n, float x[], float y[], int m, float xo[], float yo[],
float yd[], float yi[])
{

int   i;
float yb, yt, ypos_top = 0.88;

Gcolr_rep rgb;
Gpoint plist[IDIM];
Gpoint_list pmk;

/*
*  Open GKS, open and activate a workstation.
*/
gopen_gks("stdout",0);
gopen_ws(WKID, NULL, IWTYPE);
gactivate_ws(WKID);

/*
* Define a color table.
*/
rgb.rgb.red = rgb.rgb.green = rgb.rgb.blue = 1.;
gset_colr_rep(WKID,0,&rgb);
rgb.rgb.red = rgb.rgb.green = rgb.rgb.blue = 0.;
gset_colr_rep(WKID,1,&rgb);
rgb.rgb.red = 1.;
rgb.rgb.green = rgb.rgb.blue = 0.;
gset_colr_rep(WKID,2,&rgb);
rgb.rgb.red = rgb.rgb.green = 0.;
rgb.rgb.blue = 1.;
gset_colr_rep(WKID,3,&rgb);

/*
* Plot the main title.
*/
gset_clip_ind(0);
c_plchhq(.5,.95,":F25:Demo for c_ftcurv, c_ftcurvd, c_ftcurvi",0.03,0.,0.);

/*
* Graph the interpolated function values and mark the original
* input data points.
*/
yb = -1.0;
yt =  2.0;
c_bkgft1(ypos_top,"Function",yb,yt);
c_gridal(6,5,3,1,1,1,10,0.0,yb);
c_curve(xo,yo,m);

/*
*  Mark the input data points.
*/
for (i = 0; i < n; i++) {
plist[i].x = x[i];
plist[i].y = y[i];
}
gset_marker_size(2.);
gset_marker_colr_ind(3);
pmk.num_points = n;
pmk.points = plist;
gpolymarker(&pmk);

/*
*  Graph the derivatives.
*/
yb = -0.3;
yt =  0.3;
c_bkgft1(ypos_top-0.3,"Derivative",yb,yt);
c_gridal(6,5,3,1,1,1,10,0.0,yb);
c_curve(xo,yd,m);

/*
*  Graph the integral.
*/
yb = -6.0;
yt = 10.0;
c_bkgft1(ypos_top-0.6,"Integral",yb,yt);
c_gridal(6,5,4,1,1,1,10,0.0,yb);
c_curve(xo,yi,m);

c_frame();
/*
*  Deactivate and close workstation, close GKS.
*/
gdeactivate_ws(WKID);
gclose_ws(WKID);
gclose_gks();
}

void c_bkgft1(float ypos, char *label, float yb, float yt) {
c_set(0.,1.,0.,1.,0.,1.,0.,1.,1);
c_pcseti("fn",21);
c_plchhq(.2,ypos-0.03,label,0.025,0.,-1.0);
c_set(0.13,0.93,ypos-0.2,ypos,0.0,30.0, yb, yt, 1);
gset_line_colr_ind(2);
c_line(0.,0.,30.,0.);
c_sflush();
gset_line_colr_ind(1);
c_gaseti("lty",1);
c_pcseti("fn",21);
c_gasetr("xls",0.02);
c_gasetc("xlf","(i3)");
c_gasetr("yls",0.02);
c_gasetc("ylf","(f5.1)");
c_gasetr("xmj",0.02);
c_gasetr("ymj",0.02);
}
```

home | contents | defs | params | procedures | exmpls