CSSTRI - calculates a Delaunay triangulation for data on a sphere

       To use CSSTRI, 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                                                May 2000                                      CSSTRI(3NCARG)

       N           (integer,input) The number of input data points (N > 2).

       RLAT        (real, input) An array containing the latitudes of the input data, expressed in degrees.  The
                   first three points must not be collinear (lie on a common great circle).

       RLON        (real, input) An array containing the longitudes of the input data, expressed in degrees.

       NT          (integer,  output)  The number of triangles in the triangulation, unless IER .NE. 0, in which
                   case NT = 0. Where NB is the number of boundary points on the convex hull of the data, if  NB
                   .GE.  3, then NT = 2N-NB-2, otherwise NT=2N-4. The input data are considered to be bounded if
                   they all lie in one hemisphere.  Dimensioning NT for 2*N will always work.

       NTRI        (integer, output) A two-dimensional integer array dimensioned for 3 x  NT  where  NT  is  the
                   number of triangles in the triangulation (NT is at most 2*N). NTRI contains the triangulation
                   data.   The   vertices   of   the   Kth   triangle   are:  (PLAT(NTRI((1,K)),PLON(NTRI(1,K)),
                   (PLAT(NTRI((2,K)),PLON(NTRI(2,K)), (PLAT(NTRI((3,K)),PLON(NTRI(3,K))

       IWK         (integer, input) An integer workspace of length 27*N.

       RWK         (double precision, input) A work array dimensioned for 13*N.  Note that this work array  must
                   be typed DOUBLE PRECISION.

       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 cssgrid_errors for details.

       CSSTRI - calculates a Delaunay triangulation for data on a sphere

       css_overview, cssgrid, csvoro.

       Complete documentation for Cssgrid is available at URL
       http://ngwww.ucar.edu/ngdoc/ng/ngmath/cssgrid/csshome.html

       CALL CSSTRI (N, RLAT, RLON, NT, NTRI, IWK, RWK, IER)

       CSSTRI is called to find a Delaunay triangulation of data randomly positioned on the surface of a sphere.