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.TH Cssgrid 3NCARG "May 2000" UNIX "NCAR GRAPHICS"
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.SH NAME
cssgrid \- fit a tension spline interpolation to a function
.SH DESCRIPTION
Cssgrid is a software package in the ngmath library that implements a 
tension spline interpolation algorithm to fit a function to input data
randomly located on the surface of a sphere.
.sp
There are user-settable parameters that control various aspects 
of the algorithm, the most important of which is the tension factor
that controls the level a tautness of the spline fit.  This varies
from pure cubic spline interpolation for a tension factor of 0. to near linear
interpolation for a large tension factor.  By default, the tension
factor is automatically computed to optimize certain fitting criteria.
.sp
The output is a set of values at coordinates on a user-specified 
lat/lon grid (which can be a single point).
Procedures also exist for finding a Dealunay triangulation and
Voronoi polygons.
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Functionally equivalent Fortran, C, and NCL interfaces are provided. 
Fortran and C codes are available in both single and double precision.
.sp
Cssgrid is based on the work of Robert Renka and his packages
STRIPACK and SSRFPACK.
.SH SYNOPSIS
.sp
Fortran
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-----------------------------
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 CSSGRID  - interpolation on a sphere
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 CSSTRI   - calculates Delaunay triangulation
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 CSVORO   - calculates Voronoi polygons
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 CSS2C    - converts from lat/lon to Cartesian coordinates
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 CSC2S    - converts from Cartesian to lat/lon coordinates
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 CSSETI   - set values for integer-valued parameters
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 CSGETI   - retrieve values for integer-valued parameters
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 CSSETR   - set values for real valued parameters
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 CSGETR   - retrieve values for real valued parameters
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 CSSETD   - set values for double precision-valued parameters
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 CSGETD   - retrieve values for double precision-valued parameters
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 CSSGRIDD - interpolation on a sphere (double precision entry)
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 CSSTRID  - calculates Delaunay triangulation (double precision entry)
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 CSVOROD  - calculates Voronoi polygons (double precision entry)
 CSS2CD   - converts from lat/lon to Cartesian coordinates (double precision entry)
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 CSC2SD   - converts from Cartesian to lat/lon coordinates (double precision entry)
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-----------------------------
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 c_cssgrid  - interpolation on a sphere
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 c_csstri   - calculates Delaunay triangulation
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 c_csvoro   - calculates Voronoi polygons
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 c_css2c    - converts from lat/lon to Cartesian coordinates
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 c_csc2s    - converts from Cartesian to lat/lon coordinates
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 c_csseti   - set values for integer-valued parameters
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 c_csgeti   - retrieve values for integer-valued parameters
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 c_cssetr   - set values for real valued parameters
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 c_csgetr   - retrieve values for real valued parameters
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 c_cssetd   - set values for double precision-valued parameters
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 c_csgetd   - retrieve values for double precision-valued parameters
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 c_cssgridd - interpolation on a sphere (double precision entry)
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 c_csstrid  - calculates Delaunay triangulation (double precision entry)
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 c_csvorod  - calculates Voronoi polygons (double precision entry)
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 c_css2cd   - converts from lat/lon to Cartesian coordinates (double precision entry)
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 c_csc2sd   - converts from Cartesian to lat/lon coordinates (double precision entry)
.SH ACCESS 
To use Cssgrid entries, load the NCAR Graphics library ngmath.
.SH SEE ALSO
cssgrid_params
cssgrid_errors
.sp
Complete documentation for Cssgrid is available at URL
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http://ngwww.ucar.edu/ngdoc/ng/ngmath/cssgrid/csshome.html
.SH COPYRIGHT
Copyright (C) 2000
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University Corporation for Atmospheric Research
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The use of this Software is governed by a License Agreement.