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

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

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

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

53       To use CSSTRI, load the NCAR Graphics library ngmath.
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SEE ALSO

56       css_overview, cssgrid, csvoro.
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58       Complete documentation for Cssgrid is available at URL
59       http://ngwww.ucar.edu/ngdoc/ng/ngmath/cssgrid/csshome.html
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62       Copyright (C) 2000
63       University Corporation for Atmospheric Research
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65       The use of this Software is governed by a License Agreement.
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69UNIX                               May 2000                     CSSTRI(3NCARG)
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