.help gsinit Aug85 "Gsurfit Package"
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NAME
gsinit -- initialize surface descriptor
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SYNOPSIS
include <math/gsurfit.h>

.nf
gsinit (sf, surface_type, xorder, yorder, xterms, xmin, xmax,
	ymin, ymax)
.fi

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pointer	sf		# surface descriptor
int	surface_type	# surface function
int	xorder		# order of function in x
int	yorder		# order of function in y
int	xterms		# include cross-terms? (YES/NO)
real	xmin		# minimum x value
real	xmax		# maximum x value
real	ymin		# minimum y value
real	ymax		# maximum y value
.fi
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ARGUMENTS
.ls sf    
Pointer to the surface descriptor structure.
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.ls surface_type
Fitting function. Permitted values are GS_LEGENDRE and GS_CHEBYSHEV for
Legendre and Chebyshev polynomials.
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.ls xorder, yorder
Order of the polynomial to be fit. The order must be greater than or
equal to 1. If xorder == 1 and yorder == 1 a constant is fit to the data.
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.ls xterms
Set the cross-terms type? The options are GS_XNONE (the old NO option) for
no cross terms, GS_XHALF for diagonal cross terms (new option), and GS_XFULL
for full cross terms (the old YES option).
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.ls xmin, xmax
Minimum and maximum x values. All the x values of interest including the
data x values and the x values of any surface to be evaluated must
fall in the range xmin <= x <= xmax.
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.ls ymin, ymax
Minimum and maximum y values. All the y values of interest including the
data y values and the y values of any surface to be evaluated must
fall in the range ymin <= y <= ymax.
.le
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DESCRIPTION
GSINIT allocates space for the surface descriptor and the arrays and vectors
used by the numerical routines. It initializes all arrays and vectors to zero
and returns the surface descriptor to the calling routine.
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NOTES
GSINIT must be the first GSURFIT routine called.
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SEE ALSO
gsfree
.endhelp