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authorJoseph Hunkeler <jhunkeler@gmail.com>2015-07-08 20:46:52 -0400
committerJoseph Hunkeler <jhunkeler@gmail.com>2015-07-08 20:46:52 -0400
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+.help asivector Dec98 "Image Interpolator Package"
+.ih
+NAME
+asivector -- evaluate the interpolant
+.ih
+SYNOPSIS
+asivector (asi, x, y, npix)
+
+.nf
+ pointer asi #I interpolator descriptor
+ real x[npix/2*npix] #I x array, 1 <= x[i] <= npix
+ real y[npix] #O array of interpolated values
+ int npix #I number of x values
+.fi
+.ih
+ARGUMENTS
+.ls asi
+Pointer to the sequential interpolator descriptor structure.
+.le
+.ls x
+Array of npix x values, or array of npix x ranges if the interpolant is
+drizzle.
+.le
+.ls y
+Array of interpolated values.
+.le
+.ls npix
+The number of x values.
+.le
+.ih
+DESCRIPTION
+The polynomial coefficients are calculated directly from the data points
+for the polynomial interpolants, and from the B-spline coefficients for
+the cubic spline interpolant. The actual calculation is done by adding and
+multiplying terms according to Everett's central difference interpolation
+formula. The boundary extension algorithm is projection.
+
+The sinc interpolant is computed using a range of data points around
+the desired position. Look-up table sinc interpolation is computed
+using the most appropriate entry in a precomputed look-up table.
+The boundary extension algorithm is nearest neighbor.
+
+The drizzle interpolant is computed by summing the data over the user
+supplied X intervals.
+.ih
+NOTES
+Checking for out of bounds and INDEF valued pixels is the responsibility of the
+user. ASIINIT or ASISINIT and ASIFIT must be called before calling ASIVECTOR.
+.ih
+SEE ALSO
+asieval, asider, arieval, arider
+.endhelp