.help islsolve Apr85 "Surfit Package"
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NAME
islsolve -- solve the equations for a surface grid line
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SYNOPSIS
include <math/surfit.h>

islsolve (sf, lineno, ier)

.nf
pointer	sf		# surface grid descriptor
int	lineno		# surface grid line number
int	ier		# error code
.fi
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ARGUMENTS
.ls sf     
Pointer to the surface grid descriptor structure.
.le
.ls lineno
The number of the surface grid line to be added to the dataset.
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.ls ier      
Error code returned by the fitting routines. The options are OK, SINGULAR,
and NO_DEG_FREEDOM. If ier = SINGULAR the matrix is singular, ISLSOLVE
will compute a solution to the normal equations but one or more of the
coefficients will be zero. If ier = NO_DEG_FREEDOM, too few data points
exist for a reasonable solution to be computed and ISLSOLVE returns without
fitting the data.
.le
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DESCRIPTION
ISLSOLVE computes the Cholesky factorization of the data matrix and
solves for the coefficients
of the x fitting function by forward and back substitution.
An error code is
returned by ISLSOLVE if it is unable to solve the normal equations as
formulated.
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NOTES
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SEE ALSO
isinit, islfit, islrefit, islaccum, islzero, issolve, isfree
.endhelp