.help msivector Dec98 "Image Interpolation Package"
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NAME
msivector -- evaluate the interpolant at an array of x and y points
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SYNOPSIS
msivector (msi, x, y, zfit, npts)

.nf
    pointer	msi		#I interpolant descriptor
    real	x[npts/4*npts]	#I x values, 1 <= x <= nxpix
    real	y[npts/4*npts]	#I y values, 1 <= y <= nypix
    real	zfit[npts]	#O interpolated values
    int		npts		#I number of points
.fi
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ARGUMENTS
.ls msi    
The pointer to the sequential interpolant descriptor
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.ls x, y
The array of x and y values at or in the case tof the drizzle interpolant the
array of quadrilaterals over which to evaluate the interpolant.
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.ls zfit
The interpolated values.
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.ls npts
The number of points.
.le
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DESCRIPTION
The polynomial coefficients are calculated directly from the data points,
The polynomial interpolants are evaluated using Everett's central difference
formula. The spline interpolant uses the B-spline coefficients
calculated using the MSIFIT routine. The boundary extension algorithm is
projection.

The sinc interpolant is evaluated using a array of data points around
the point in question. The look-up table since is computed by convolving
the data with a pre-computed look-up table entry. The boundary extension
algorithm is nearest neighbor.

The drizzle interpolant is evaluated by summing the data over the
list of user supplied quadrilaterals.
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NOTES
Checking for out of bounds and INDEF valued pixels is the responsibility
of the user. MSIINIT or MSISINIT and MSIFIT must be called before using
MSIVECTOR.
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SEE ALSO
msieval, mrieval
.endhelp