DSPNT3D - Interpolate at a single point (or points) in 3D in double precision

       To use DSPNT3D, 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                                           September 1997-1998                               DSPNT3D(3NCARG)

       N           (Integer, Input) - The number of input data points.

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

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

       Z           (Double precision, Input) - An array containing the Z coordinates of the input data points.

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

       M           (Integer, Input) - The number of output data points (this may be "1").

       XO          (Double  precision,  Input)  -  An  array  of dimension M containing the X coordinates of the
                   output data. The values in XO may be in any order.

       YO          (Double precision, Input) - An array of dimension M  containing  the  Y  coordinates  of  the
                   output data. The values in YO may be in any order.

       ZO          (Double  precision,  Input)  -  An  array  of dimension M containing the Z coordinates of the
                   output data. The values in ZO may be in any order.

       UO          (Double precision, output) - An array of dimension  M  containing  the  interpolated  values.
                   UO(I) is the interpolated value at point (XO(I),YO(I),ZO(I)) for I=1,M.

       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 dsgrid_errors for details.

       DSPNT3D - Interpolate at a single point (or points) in 3D in double precision

       dsgrid, dsgrid_params.

       Complete documentation for Dsgrid is available at URL
       http://ngwww.ucar.edu/ngdoc/ng/ngmath/dsgrid/dshome.html

       CALL DSPNT3D (N, X, Y, Z, U, M, XO, YO, ZO, UO, IER)

       This subroutine is called when you want to interpolate at an individual point or points.