NAME

       c_shgrid - interpolate random data in 3-space using a modified Shepard's algorithm

FUNCTION PROTOTYPE

       float *c_shgrid(int, float [], float [], float [], float [],
                       int, int, int, float [], float [], float [], int*);

SYNOPSIS

       float *c_shgrid (n, x[], y[], z[], f[], nxo, nyo, nzo,
                        xo[], yo[], zo[], ier);

DESCRIPTION

       n           (integer,input) The number of input data points (n > 9).

       xi          (float,  input)  An array dimensioned for n containing the X coordinate values
                   for the input function.

       yi          (float, input) An array dimensioned for n containing the Y  coordinate  values
                   for the input function.

       zi          (float,  input)  An array dimensioned for n containing the Z coordinate values
                   for the input function.

       f           (float, input) An array containing the functional values of the input function
                   -- f[k] is the functional value at (xi[k], yi[k], zi[k]) for k=0,n-1.

       nxo         (integer,  input)  The  number of X coordinate values to be calculated for the
                   output grid.

       nyo         (integer, input) The number of Y coordinate values to be  calculated  for  the
                   output grid.

       nzo         The number of Z coordinate values to be calculated for the output grid.

       xo          (float,  input)  An  array dimensioned for nxo containing the X coordinates of
                   the output grid.

       yo          (float, output) An array dimensioned for nyo containing the Y  coordinates  of
                   the output grid.

       zo          (float,  output)  An array dimensioned for nzo containing the Z coordinates of
                   the output grid.

       ier         (pointer to integer, output) An error return value.  If *ier is returned as 0,
                   then  no  errors  were  detected. If *ier is non-zero, then refer to the error
                   list in the error table for details.

USAGE

       c_shgrid is called to interpolate randomly  spaced  data  in  3-space.   c_shgrid  uses  a
       modified Shepard's algorithm to construct an interpolatory surface.

       c_shgrid returns a pointer to a linear array of data that is the interpolation grid stored
       in row-major order. That is, if out is declared as

         float *out;

       and we set:

         out = c_shgrid(n, x, y, z, f, nxo, nyo, nzo, xo, yo, zo, ier);

       then out[nz*ny*i + nz*j + k] is the  approximation  function  value  at  coordinate  point
       (xo[i],  yo[j], zo[k]) for 0 <= i < nx, 0 <= j < ny, and 0 <= k < nz. The space for out is
       allocated internal to c_shgrid and is nx*ny*nz floats in size.

ACCESS

       To use c_shgrid, load the NCAR Graphics library ngmath.

SEE ALSO

       shgrid_params, c_shseti, c_shgeti, c_shgetnp.

       Complete documentation for Shgrid is available at URL
       http://ngwww.ucar.edu/ngdoc/ng/ngmath/shgrid/shhome.html

COPYRIGHT

       Copyright (C) 1997-2000
       University Corporation for Atmospheric Research

       The use of this Software is governed by a License Agreement.