1CSSTRID(3NCARG)                  NCAR GRAPHICS                 CSSTRID(3NCARG)
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NAME

6       CSSTRID - calculates a Delaunay triangulation for data on a sphere
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SYNOPSIS

9       CALL CSSTRID (N, RLAT, RLON, NT, NTRI, IWK, RWK, IER)
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DESCRIPTION

12       N           (integer,input) The number of input data points (N > 2).
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14       RLAT        (double precision, input) An array containing the latitudes
15                   of the input data, expressed in degrees.  The  first  three
16                   points  must  not  be collinear (lie on a common great cir‐
17                   cle).
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19       RLON        (double precision, input) An array  containing  the  longi‐
20                   tudes of the input data, expressed in degrees.
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22       NT          (integer, output) The number of triangles in the triangula‐
23                   tion, unless IER .NE. 0, in which case NT = 0. Where NB  is
24                   the  number  of  boundary  points on the convex hull of the
25                   data, if NB .GE. 3, then NT = 2N-NB-2,  otherwise  NT=2N-4.
26                   The input data are considered to be bounded if they all lie
27                   in one hemisphere.  Dimensioning NT  for  2*N  will  always
28                   work.
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30       NTRI        (integer,  output)  A  two-dimensional integer array dimen‐
31                   sioned for 3 x NT where NT is the number  of  triangles  in
32                   the  triangulation  (NT  is at most 2*N). NTRI contains the
33                   triangulation data. The vertices of the Kth  triangle  are:
34                   (PLAT(NTRI((1,K)),PLON(NTRI(1,K)),
35                   (PLAT(NTRI((2,K)),PLON(NTRI(2,K)),
36                   (PLAT(NTRI((3,K)),PLON(NTRI(3,K))
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38       IWK         (integer, input) An integer workspace of length 27*N.
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40       RWK         (double  precision,  input)  A  work  array dimensioned for
41                   13*N.  Note that this work array must be typed DOUBLE  PRE‐
42                   CISION.
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44       IER         (integer,  output)  An  error  return  value.   If  IER  is
45                   returned as 0, then no errors were detected. If IER is non-
46                   zero,  then  refer  to  the man page for cssgrid_errors for
47                   details.
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USAGE

50       CSSTRID is called to find a Delaunay  triangulation  of  data  randomly
51       positioned  on  the  surface of a sphere. CSSTRID is a double precision
52       version of CSSTRI.
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ACCESS

55       To use CSSTRID, load the NCAR Graphics library ngmath.
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SEE ALSO

58       css_overview, cssgrid, csstri, csvoro.
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60       Complete documentation for Cssgrid is available at URL
61       http://ngwww.ucar.edu/ngdoc/ng/ngmath/cssgrid/csshome.html
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64       Copyright (C) 2000
65       University Corporation for Atmospheric Research
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67       The use of this Software is governed by a License Agreement.
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71UNIX                               May 2000                    CSSTRID(3NCARG)
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