ncl_css_overview

Langue: en

Version: May 2000 (fedora - 05/07/09)

Section: 3 (Bibliothèques de fonctions)

Sommaire

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
-----------------------------

 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)
-----------------------------

 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.

SEE ALSO

cssgrid_params cssgrid_errors

Complete documentation for Cssgrid is available at URL
http://ngwww.ucar.edu/ngdoc/ng/ngmath/cssgrid/csshome.html

Copyright (C) 2000
University Corporation for Atmospheric Research

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