c_cssgrid - tension spline interpolation on a sphere
float *c_cssgrid(int, float [], float [], float [],
int, int, float [], float [], int *);
float *c_cssgrid (n, rlat, rlon, f, ni, nj, plat, plon, ier)
- n
- The number of input data points, n > 2.
- rlat
- An array containing the latitudes of the input data,
expressed in degrees. The first three points must not be collinear (lie on
a common great circle).
- rlon
- An array containing the longitudes of the input data,
expressed in degrees.
- f
- Array containing data values. f[i] is the functional value
at (rlat[i],rlon[i]) for i = 0 to n-1.
- ni
- The number of latitudes in the interpolated grid.
- nj
- The number of longitudes in the interpolated grid. ni and
nj can both be 1, allowing for interpolation at a single point.
- plat
- An array containing the latitudes of the points where
interpolated values are to be computed. The values in plat should be in
degrees.
- plon
- An array of length nj containing the longitudes the output
grid lines. The values in plon should be in degrees.
- ier
- An error return value. If *ier is returned as 0, then no
errors were detected. If *ier is non-zero, then refer to the error list in
cssgrid_errors for details.
c_cssgrid is called to find an interpolating tension spline for randomly
positioned data on a unit sphere.
c_cssgrid returns a pointer to a linear array of data that contains interpolated
values at user-specified lat/lon pairs. The returned array stores its values
as if they were a 2-dimensional C array with latitude being the first
dimension and longitude the second dimension. That is, if out is declared as
float *out;
and we set:
out = c_cssgrid(n, rlat, rlon, f, nlat, nlon, plat, plon, &ier);
then out[i*nlon+j] is the interpolated function value at coordinate point
(plat[i], plon[j]) for 0 <= i < nlat and 0 <= j < nlon. The space
for out is allocated internal to c_cssgrid and is nlat * nlon floats in size.
To use c_cssgrid, load the NCAR Graphics library ngmath.
css_overview, 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.