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

6       Cssgrid is a software package in the ngmath library that implements a
7       tension spline interpolation algorithm to fit a function to input data
8       randomly located on the surface of a sphere.
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10       There are user-settable parameters that control various aspects of the
11       algorithm, the most important of which is the tension factor that
12       controls the level a tautness of the spline fit.  This varies from pure
13       cubic spline interpolation for a tension factor of 0. to near linear
14       interpolation for a large tension factor.  By default, the tension
15       factor is automatically computed to optimize certain fitting criteria.
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17       The output is a set of values at coordinates on a user-specified
18       lat/lon grid (which can be a single point).  Procedures also exist for
19       finding a Dealunay triangulation and Voronoi polygons.
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21       Functionally equivalent Fortran, C, and NCL interfaces are provided.
22       Fortran and C codes are available in both single and double precision.
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24       Cssgrid is based on the work of Robert Renka and his packages STRIPACK
25       and SSRFPACK.
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SYNOPSIS

28       Fortran
29       -----------------------------
30        CSSGRID  - interpolation on a sphere
31        CSSTRI   - calculates Delaunay triangulation
32        CSVORO   - calculates Voronoi polygons
33        CSS2C    - converts from lat/lon to Cartesian coordinates
34        CSC2S    - converts from Cartesian to lat/lon coordinates
35        CSSETI   - set values for integer-valued parameters
36        CSGETI   - retrieve values for integer-valued parameters
37        CSSETR   - set values for real valued parameters
38        CSGETR   - retrieve values for real valued parameters
39        CSSETD   - set values for double precision-valued parameters
40        CSGETD   - retrieve values for double precision-valued parameters
41        CSSGRIDD - interpolation on a sphere (double precision entry)
42        CSSTRID  - calculates Delaunay triangulation (double precision entry)
43        CSVOROD  - calculates Voronoi polygons (double precision entry)
44        CSS2CD   - converts from lat/lon to Cartesian coordinates (double
45       precision entry)
46        CSC2SD   - converts from Cartesian to lat/lon coordinates (double
47       precision entry)
48       -----------------------------
49        c_cssgrid  - interpolation on a sphere
50        c_csstri   - calculates Delaunay triangulation
51        c_csvoro   - calculates Voronoi polygons
52        c_css2c    - converts from lat/lon to Cartesian coordinates
53        c_csc2s    - converts from Cartesian to lat/lon coordinates
54        c_csseti   - set values for integer-valued parameters
55        c_csgeti   - retrieve values for integer-valued parameters
56        c_cssetr   - set values for real valued parameters
57        c_csgetr   - retrieve values for real valued parameters
58        c_cssetd   - set values for double precision-valued parameters
59        c_csgetd   - retrieve values for double precision-valued parameters
60        c_cssgridd - interpolation on a sphere (double precision entry)
61        c_csstrid  - calculates Delaunay triangulation (double precision
62       entry)
63        c_csvorod  - calculates Voronoi polygons (double precision entry)
64        c_css2cd   - converts from lat/lon to Cartesian coordinates (double
65       precision entry)
66        c_csc2sd   - converts from Cartesian to lat/lon coordinates (double
67       precision entry)
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ACCESS

70       To use Cssgrid entries, load the NCAR Graphics library ngmath.
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SEE ALSO

73       cssgrid_params cssgrid_errors
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75       Complete documentation for Cssgrid is available at URL
76       http://ngwww.ucar.edu/ngdoc/ng/ngmath/cssgrid/csshome.html
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79       Copyright (C) 2000
80       University Corporation for Atmospheric Research
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82       This documentation is free software; you can redistribute it and/or
83       modify it under the terms of the GNU General Public License as
84       published by the Free Software Foundation; either version 2 of the
85       License, or (at your option) any later version.
86
87       This software is distributed in the hope that it will be useful, but
88       WITHOUT ANY WARRANTY; without even the implied warranty of
89       MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
90       General Public License for more details.
91
92       You should have received a copy of the GNU General Public License along
93       with this software; if not, write to the Free Software Foundation,
94       Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
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99UNIX                               May 2000                    Cssgrid(3NCARG)
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