NAME¶
c_csa2ls - cubic spline approximation, simple entry for two-dimensional input,
list output
FUNCTION PROTOTYPE¶
float *c_csa2ls(int, float [], float [], float [], int [],
int, float [], float [], int *);
SYNOPSIS¶
int c_csa2ls(int n, float xi[], float yi[], float zi[], int knots[2],
int no, float xo[], float yo[], int *ier);
DESCRIPTION¶
- n
- (integer,input) The number of input data points. It must be that n is
greater than 3 and, depending on the size of knots below, n may have to be
larger.
- xi
- (real, input) An array dimensioned for n containing the X coordinate
values for the input function.
- yi
- (real, input) An array dimensioned for n containing the Y coordinate
values for the input function.
- zi
- (real, input) An array containing the functional values of the input
function -- zi[k] is the functional value at (xi[k], yi[k]) for
k=0,n-1.
- knots
- (integer, input) The number of knots to be used in constructing the
approximation spline. knots[0] and knots[1] must be at least 4. The larger
the value for knots, the closer the approximated curve will come to
passing through the input function values.
- no
- (integer, input) The number of X - Y coordinate values to be calculated
for the output array.
- xo
- (real, input) An array dimensioned for no containing the X coordinates of
the output list.
- yo
- (real, output) An array dimensioned for no containing the Y coordinates of
the output list.
- ier
- (pointer to integer, output) 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 the error table for details.
USAGE¶
c_csa2ls is called to find values of an approximating cubic spline at specified
two-dimensional coordinates. If you want to weight the input data values,
calculate derivatives, or handle data sparse areas specially, then you will
need to use c_csa2lxs.
c_csa2ls returns a pointer to a linear array of data that contains the
approximated values calculated at the input list of coordinate values. That
is, if out is declared as
float *out;
and we set:
out = c_csa2ls(n, x, y, z, knots, no, xo, yo, &ier);
then out[i] is the approximated function value at coordinate point (xo[i],
yo[i]) for 0 <= i < no. The space for out is allocated internal to
c_csa2ls and is no floats in size.
ACCESS¶
To use c_csa2ls, load the NCAR Graphics library ngmath.
SEE ALSO¶
csagrid, c_csa2s, c_csa2xs, c_csa2lxs
Complete documentation for Csagrid is available at URL
http://ngwww.ucar.edu/ngdoc/ng/ngmath/csagrid/csahome.html
COPYRIGHT¶
Copyright (C) 2000
University Corporation for Atmospheric Research
The use of this Software is governed by a License Agreement.