Values for these parameters can be set by using the subroutines CSSETI, CSSETR, CSSETD for Fortran programs or the functions c_csseti, c_cssetr, and c_cssetd for C programs. or cssetp for NCL.
More in-depth understanding of the parameter settings can be obtained from reading Dr. Renka's articles in the ACM Transactions on Mathematical Software, Vol. 23, No 3, September 1997.
| Parameter name | Parameter type | Description | Legal values | Default value |
|---|---|---|---|---|
| sig | float | value of the tension factor for the splines | any non-negative value (0. yields cubic splines; large values yield linear interpolation) | 1. |
| tol | float | Tolerance to use in calculating gradient differences to terminate the iteration sequence when computing global gradients | any positive value. | 0.01 |
| ttf | float | Tolerance to use in determining how accurately each tension factor should be calculated to approximate its optimum value | any positive value. | 0.01 |
| nls | int | Number of nodes to use in the least squares fit. | greater than or equal to 4 | 10 |
| nsg | int | Maximum number of iterations to use in the algorithm for computing automatic tension factors | greater than or equal to 2 | 10 |
| isg | int | Flag to revert to calculating automatic tension factors rather than use a constant tension. Using a constant tension is effected by setting a value for the control parameter sig. If isg is 0, then a tension array is used, otherwise a constant tension is used. | Any integer | 0 |
| igr | int | Flags whether global or local gradients are used (1 implies global, anything else implies local). | Any integer | 1 |
| mvl | float | Fill value to use in returns for NCL functions. Used only if mvl has been changed from its default. | Any float | -8. |