/*****************************************************************************
*                                                                            *
*   SPLINE2.SPL  Copyright (C) 1997-2000  DSP Development Corporation        *
*                               All Rights Reserved                          *
*                                                                            *
*   Author:      Randy Race                                                  *
*                                                                            *
*   Synopsis:    2 Dimensional cubic spline interpolation                    *
*                                                                            *
*   Revisions:   21 Jun 1997  RRR  Creation                                  *
*                 1 Jun 2000  RRR  default to series spline                  *
*                                                                            *
*****************************************************************************/

#include 


#if @HELP_SPLINE2

    SPLINE2

    Purpose: Performs 2 dimensional cubic spline fitting

    Syntax:  SPLINE2(array, numrows, numcols)

              array   - input array to interpolate
              numrows - an integer specifying the row interpolation factor
              numcols - an optional integer for the column interpolation
                        factor (default numrows)

    Returns: An array

    Example:

             W1: Ravel(gnorm(100, 1), 10);
             W2: Spline2(W1, 4);

             W2 contains a 37x37 array of interpolated values.


    Remarks:
             The interpolated result from Spline2 always passes through
             the original data points.

    See Also
             Contour
             Interp
             Interp2
             Plot3d
             Ravel
             Spline
             Waterfall

#endif


spline2(s, n, m)
{
        local u;

        if (argc < 3)
        {
                if (argc < 2)
                {
                        if (argc < 1) error("spline2 - array required");
                        
                        /* interpolation factor */
                        n = 2;
                }
                else
                {
                        n = castint(n);
                }
                
                m = n;
        }

        /* check input array */
        if (isarray(s))
        {
                if (numcols(s) < 2)
                {
                        /* regular series */
                        return(spline(s, n));
                }
        }
        else error("spline2 - array required");

        /* spline in Y direction */
        u = spline(s', m);

        /* spline in X direction */
        u = spline(u', n);

        return(u);
}