.help iseval Apr85 "Surfit Package"
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NAME
iseval -- evaluate the fitted surface at x and y
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SYNOPSIS
y = iseval (sf, x, y)

.nf
pointer	sf		# surface descriptor
real	x		# x value, 1 <= x <= ncols
real	y		# y value, 1 <= y <= nlines
.fi
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ARGUMENTS
.ls sf      
Pointer to the surface descriptor structure.
.le
.ls x, y
X and y values at which the surface is to be evaluated.
.le
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DESCRIPTION
Evaluate the surface at the specified value of x and y. ISEVAL is a real
valued function which returns the fitted value.
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NOTES
ISEVAL uses the coefficient array stored in the surface descriptor structure.
Checking for out of bounds x and y values is the responsibility of the calling
program.
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SEE ALSO
isvector
.endhelp