CSSTRI - calculates a Delaunay triangulation for data on a
sphere
CALL CSSTRI (N, RLAT, RLON, NT, NTRI, IWK, RWK, IER)
- 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 is called to find a Delaunay triangulation of data randomly
positioned on the surface of a sphere.
To use CSSTRI, load the NCAR Graphics library ngmath.
css_overview, cssgrid, csvoro.
Complete documentation for Cssgrid is available at URL
http://ngwww.ucar.edu/ngdoc/ng/ngmath/cssgrid/csshome.html
Copyright (C) 2000
University Corporation for Atmospheric Research
The use of this Software is governed by a License Agreement.