/*****************************************************************************
*                                                                            *
*   INTERP2.SPL  Copyright (C) 1997 DSP Development Corporation              *
*                               All Rights Reserved                          *
*                                                                            *
*   Author:      Randy Race                                                  *
*                                                                            *
*   Synopsis:    2 Dimensional linear interpolation                          *
*                                                                            *
*   Revisions:   21 Jun 1997  RRR  Creation                                  *
*                                                                            *
*****************************************************************************/

#include 


#if @HELP_INTERP2

    INTERP2

    Purpose: Performs 2 dimensional linear interpolation

    Syntax:  INTERP2(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: Interp2(W1, 4);

             W2 contains a 37x37 array of linearly interpolated values.


    Remarks:
             The interpolated result from INTERP2 always passes through
             the original data points.

    See Also
             Contour
             Interp
             Plot3d
             Ravel
             Spline
             Spline2
             Waterfall

#endif



interp2(s, n, m)
{
        local u;

        /* check input array */
        if (isarray(s))
        {
                if (numcols(s) < 2)
                {
                        error("interp2 - array required");
                }
        }
        else
        {
                error("interp2 - array required");
        }

        /* interpolation factor */
        if (argc < 2)
        {
                n = 2;
        }
        else
        {
                n = castint(n);
        }
        
        if (argc < 3)
        {
                m = n;
        }

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

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

        return(u);
}