.help asigrl Dec98 "Image Interpolator Package"
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NAME
asigrl -- integrate interpolant from a to b
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SYNOPSIS
integral = asigrl (asi, a, b)

.nf
    pointer	asi	#I interpolant descriptor
    real	a	#I lower limit for integral, 1 <= a <= npix
    real	b	#I upper limit for integral, 1 <= b <= npix
.fi
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ARGUMENTS
.ls asi  
Pointer to the sequential interpolant descriptor structure.
.le
.ls a
Lower limit to the integral, where 1 <= a <= npix.
.le
.ls b
Upper limit to the integral, where 1 <= b <= npix.
.le
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DESCRIPTION
The integral is calculated assuming that the interior polynomial, sinc, and
drizzle interpolants are stored as the data points, and that the spline
interpolant is stored as an array of B-spline coefficients.

The integral of the sinc interpolant is computed by dividing the integration
interval into a number of equal size subintervals which are at most one pixel
wide. The integral of each subinterval is the central value times the interval
width. The look-up table sinc interpolant is not supported and defaults to
the sinc interpolant.
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NOTES
ASIINIT or ASISINIT and ASIFIT must be called before using ASIGRL.
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SEE ALSO