.help arieval Dec98 "Image Interpolator Package"
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NAME
arieval -- evaluate the interpolant at x
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SYNOPSIS
include <math/iminterp.h>

y = arieval (x, datain, npix, interp_type)

.nf
    real	x[2]		#I x value, 1 <= x[1-2] <= npix
    real	datain[npix]	#I data values
    int		npix		#I number of data values
    int		interp_type	#I interpolant type
.fi
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ARGUMENTS
.ls x      
Single X value, or a pair of X values specifying a range in the case
of the drizzle interpolant.
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.ls datain  
Array of input data.
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.ls npix
Number of data points.
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.ls interp_type
Interpolant type. Options are II_NEAREST, II_LINEAR, II_POLY3, II_POLY5,
II_SPLINE3, II_SINC / II_LSINC, and II_DRIZZLE, for nearest neighbor,
linear, 3rd and fifth order polynomials, cubic spline, sinc, look-up
table sinc, and drizzle interpolants respectively. The look-up table sinc
interpolant is not supported and defaults to the sinc interpolant. The sinc
width is 31 pixels. The drizzle pixel fraction is 1.0. The interpolant
type definitions are contained in the package header file math/iminterp.h
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DESCRIPTION
ARIEVAL allows the evaluation of a few interpolated points without the
storage required for the sequential interpolant.
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NOTES
Checking for out of bounds and INDEF valued pixels is the responsibility of
the user.
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SEE ALSO
arider, asieval, asivector