NATGRIDS - primary single precision Fortran entry for natural neighbor gridding

       To use NATGRIDS, load the NCAR Graphics library ngmath.

       Copyright (C) 2000
       University Corporation for Atmospheric Research

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

UNIX                                             March 1997-1998                                NATGRIDS(3NCARG)

       NPNTS       (Integer, Input) - The number of input data points. (NPNTS > 3).

       X           (Real, Input) - An array containing the X coordinates of the input data points.

       Y           (Real, Input) - An array containing the Y coordinates of the input data points.

       Z           (Real,  Input) - An array containing the functional values of the input data points. That is,
                   Z(L) is the value of the input function at coordinate (X(L),Y(L)), for L=1,NPNTS.

       NUMXOUT     (Integer, Input) - The number of X values in the output grid.

       NUMYOUT     (Integer, Input) - The number of Y values in the output grid.

       XI          (Real, Input) - An array of dimension NUMXOUT containing the X coordinates of the output data
                   grid. The values in XI must be increasing, but need not be equally spaced.

       YI          (Real, Input) - An array of dimension NUMYOUT containing the Y coordinates of the output data
                   grid. The values in YI must be increasing, but need not be equally spaced.

       ZI          (Real, Output) -  A two-dimensional array of  dimension  NUMXOUT  x  NUMYOUT  containing  the
                   interpolated   functional   values.   ZI(I,J)   is  the  interpolated  value  at  grid  point
                   (XI(I),YI(J)).

       IER         (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 man page for natgrid_errors for details.

       NATGRIDS - primary single precision Fortran entry for natural neighbor gridding

       natgrid, natgrid_params, nnseti, nngeti, nnsetr, nngetr, nnsetc, nngetc.

       Complete documentation for Natgrid is available at URL
       http://ngwww.ucar.edu/ngdoc/ng/ngmath/natgrid/nnhome.html

       CALL NATGRIDS (NPNTS, X, Y, Z, NUMXOUT, NUMYOUT, XI, YI, ZI, IER)

       NATGRIDS  is  the single precision gridding function in the Natgrid package.  The behavior of NATGRIDS is
       controlled by values set for the various  parameters  described  in  natgrid_params.   Values  for  these
       parameters can be set using the subroutines NNSETI, NNSETR, and NNSETC.