.help cvrefit Jun84 "Curfit Package"
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NAME
cvrefit -- refit new y vector using old x vector and weights
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SYNOPSIS
cvrefit (cv, x, y, w, ier)

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pointer	cv		# curve descriptor
real	x[]		# array of x values
real	y[]		# array of y values
real	weight[]	# array of weights
int	ier		# error code
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ARGUMENTS
.ls cv
Pointer to the curve descriptor
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.ls x  
Array of x values.
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.ls y    
Array of y values.
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.ls weight
Array of weights.
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.ls ier  
Error code. The options are OK, SINGULAR and NO_DEG_FREEDOM. If ier equals
singular a solution is computed but one or more of the coefficients may
be zero. If ier equals NO_DEG_FREEDOM, there are insufficient data points
to compute a solution and CVREFIT returns without solving for the coefficients.
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DESCRIPTION
In some application the x and weight values remain unchanged from fit to fit
and only the y values vary. In this case it is redundant to reaccumulate
the matrix and perform the Cholesky factorization. CVREFIT 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.
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NOTES
In the first call to CVREFIT space is allocated for the non-zero basis
functions. Subsequent call to CVREFIT reference this array to avoid
recaculating basis functions at every call.
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SEE ALSO
cvfit, cvaccum, cvsolve, cvchoslv
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