ncl_css_overview (3) - Linux Manuals

NAME

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.

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.

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.

Functionally equivalent Fortran, C, and NCL interfaces are provided. Fortran and C codes are available in both single and double precision.

Cssgrid is based on the work of Robert Renka and his packages STRIPACK and SSRFPACK.

SYNOPSIS

Fortran
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 CSSGRID  - interpolation on a sphere

 CSSTRI   - calculates Delaunay triangulation

 CSVORO   - calculates Voronoi polygons

 CSS2C    - converts from lat/lon to Cartesian coordinates

 CSC2S    - converts from Cartesian to lat/lon coordinates

 CSSETI   - set values for integer-valued parameters

 CSGETI   - retrieve values for integer-valued parameters

 CSSETR   - set values for real valued parameters

 CSGETR   - retrieve values for real valued parameters

 CSSETD   - set values for double precision-valued parameters

 CSGETD   - retrieve values for double precision-valued parameters

 CSSGRIDD - interpolation on a sphere (double precision entry)

 CSSTRID  - calculates Delaunay triangulation (double precision entry)

 CSVOROD  - calculates Voronoi polygons (double precision entry)
 CSS2CD   - converts from lat/lon to Cartesian coordinates (double precision entry)

 CSC2SD   - converts from Cartesian to lat/lon coordinates (double precision entry)
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 c_cssgrid  - interpolation on a sphere

 c_csstri   - calculates Delaunay triangulation

 c_csvoro   - calculates Voronoi polygons

 c_css2c    - converts from lat/lon to Cartesian coordinates

 c_csc2s    - converts from Cartesian to lat/lon coordinates

 c_csseti   - set values for integer-valued parameters

 c_csgeti   - retrieve values for integer-valued parameters

 c_cssetr   - set values for real valued parameters

 c_csgetr   - retrieve values for real valued parameters

 c_cssetd   - set values for double precision-valued parameters

 c_csgetd   - retrieve values for double precision-valued parameters

 c_cssgridd - interpolation on a sphere (double precision entry)

 c_csstrid  - calculates Delaunay triangulation (double precision entry)

 c_csvorod  - calculates Voronoi polygons (double precision entry)

 c_css2cd   - converts from lat/lon to Cartesian coordinates (double precision entry)

 c_csc2sd   - converts from Cartesian to lat/lon coordinates (double precision entry)

ACCESS

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

COPYRIGHT

Copyright (C) 2000
University Corporation for Atmospheric Research

The use of this Software is governed by a License Agreement.