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.help gsrefit Aug85 "Gsurfit Package"
.ih
NAME
gsrefit -- refit with new z vector using old x, y and weight vector
.ih
SYNOPSIS
include < math/gsurfit.h>
gsrefit (sf, x, y, z, w, ier)
.nf
pointer sf # surface descriptor
real x[ARB] # x array, xmin <= x[i] <= xmax
real y[ARB] # y array, ymin <= y[i] <= ymax
real z[ARB] # array of data values
real w[ARB] # array of weights
int ier # error code
.fi
.ih
ARGUMENTS
.ls sf
Pointer to the surface descriptor structure.
.le
.ls x, y
Array of x and y values.
.le
.ls z
Array of data values.
.le
.ls w
Array of weights.
.le
.ls ier
Error code. The options are OK, SINGULAR and NO_DEG_FREEDOM. If ier =
SINGULAR a solution is computed but one or more coefficients may be zero.
If ier equals NO_DEG_FREEDOM, there are insufficient data points to
compute a solution and GSREFIT returns without solving for the coefficients.
.le
.ih
DESCRIPTION
In some applications the x, y and weight values remain unchanged from fit
to fit and only the z values vary. In this case it is redundant to
reaccumulate the matrix and perform the Cholesky factorization. GSREFIT
zeros and reaccumulates the vector on the right hand side of the matrix
equation and performs the forward and back substitution phase to fit for
a new coefficient vector.
.ih
NOTES
In the first call to GSREFIT space is allocated for the non-zero basis
functions. Subsequent calls to GSREFIT reference this array to avoid
recalculating basis functions at every call.
.ih
SEE ALSO
gsfit, gsaccum, gsacpts, gssolve
.endhelp
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