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# Copyright(c) 1986 Association of Universities for Research in Astronomy Inc.
include <math/iminterp.h>
include "im1interpdef.h"
define TEMP Memr[P2P($1)]
# ASIFIT -- Fit the interpolant to the data.
procedure asifit (asi, datain, npix)
pointer asi # interpolant descriptor
real datain[ARB] # data array
int npix # nunber of data points
int i
pointer c0ptr, cdataptr, cnptr, temp
begin
# Check the data array for size and allocate space for the coefficient
# array.
switch (ASI_TYPE(asi)) {
case II_SPLINE3:
if (npix < 4)
call error (0, "ASIFIT: too few points for SPLINE3")
else {
ASI_NCOEFF(asi) = npix + 3
ASI_OFFSET(asi) = 1
if (ASI_COEFF(asi) != NULL)
call mfree (ASI_COEFF(asi), TY_REAL)
call malloc (ASI_COEFF(asi), ASI_NCOEFF(asi), TY_REAL)
call malloc (temp, ASI_NCOEFF(asi), TY_REAL)
}
case II_POLY5:
if (npix < 6)
call error (0,"ASIFIT: too few points for POLY5")
else {
ASI_NCOEFF(asi) = npix + 5
ASI_OFFSET(asi) = 2
if (ASI_COEFF(asi) != NULL)
call mfree (ASI_COEFF(asi), TY_REAL)
call malloc (ASI_COEFF(asi), ASI_NCOEFF(asi), TY_REAL)
}
case II_POLY3:
if (npix < 4)
call error (0, "ASIFIT: too few points for POLY3")
else {
ASI_NCOEFF(asi) = npix + 3
ASI_OFFSET(asi) = 1
if (ASI_COEFF(asi) != NULL)
call mfree (ASI_COEFF(asi), TY_REAL)
call malloc (ASI_COEFF(asi), ASI_NCOEFF(asi), TY_REAL)
}
case II_DRIZZLE, II_LINEAR:
if (npix < 2)
call error (0, "ASIFIT: too few points for LINEAR")
else {
ASI_NCOEFF(asi) = npix + 1
ASI_OFFSET(asi) = 0
if (ASI_COEFF(asi) != NULL)
call mfree (ASI_COEFF(asi), TY_REAL)
call malloc (ASI_COEFF(asi), ASI_NCOEFF(asi), TY_REAL)
}
case II_SINC, II_LSINC:
if (npix < 1)
call error (0, "ASIFIT: too few points for SINC")
else {
ASI_NCOEFF(asi) = npix
ASI_OFFSET(asi) = 0
if (ASI_COEFF(asi) != NULL)
call mfree (ASI_COEFF(asi), TY_REAL)
call malloc (ASI_COEFF(asi), ASI_NCOEFF(asi), TY_REAL)
}
default:
if (npix < 1)
call error (0," ASIFIT: too few points for NEAREST")
else {
ASI_NCOEFF(asi) = npix
ASI_OFFSET(asi) = 0
if (ASI_COEFF(asi) != NULL)
call mfree (ASI_COEFF(asi), TY_REAL)
call malloc (ASI_COEFF(asi), ASI_NCOEFF(asi), TY_REAL)
}
}
# Define the pointers.
# (c0ptr + 1) points to first element in the coefficient array.
# (cdataptr + 1) points to first data element in the coefficient array.
# (cnptr + 1) points to the first element after the last data point in
# coefficient array.
c0ptr = ASI_COEFF(asi) - 1
cdataptr = ASI_COEFF(asi) - 1 + ASI_OFFSET(asi)
cnptr = cdataptr + npix
# Put data into the interpolant structure.
do i = 1, npix
COEFF(cdataptr + i) = datain[i]
# Specify the end conditions.
switch (ASI_TYPE(asi)) {
case II_SPLINE3:
# Natural end conditions - second deriv. zero
COEFF(c0ptr + 1) = 0.
COEFF(cnptr + 1) = 0.
COEFF(cnptr + 2) = 0. # if x = npts
# Fit spline - generate b-spline coefficients.
call ii_spline (COEFF(ASI_COEFF(asi)), TEMP(temp), npix)
call mfree (temp, TY_REAL)
case II_NEAREST, II_SINC, II_LSINC:
# No end conditions required.
case II_LINEAR, II_DRIZZLE:
COEFF(cnptr + 1) = 2. * COEFF(cdataptr + npix) - # if x = npts
COEFF(cdataptr + npix - 1)
case II_POLY3:
COEFF(c0ptr + 1) = 2. * COEFF(cdataptr + 1) - COEFF(cdataptr + 2)
COEFF(cnptr + 1) = 2. * COEFF(cdataptr + npix) -
COEFF(cdataptr + npix - 1)
COEFF(cnptr + 2) = 2. * COEFF(cdataptr + npix) -
COEFF(cdataptr + npix - 2)
case II_POLY5:
COEFF(c0ptr + 1) = 2. * COEFF(cdataptr + 1) - COEFF(cdataptr + 3)
COEFF(c0ptr + 2) = 2. * COEFF(cdataptr + 1) - COEFF(cdataptr + 2)
COEFF(cnptr + 1) = 2. * COEFF(cdataptr + npix) -
COEFF(cdataptr + npix - 1)
COEFF(cnptr + 2) = 2. * COEFF(cdataptr + npix) -
COEFF(cdataptr + npix - 2)
COEFF(cnptr + 3) = 2. * COEFF(cdataptr + npix) -
COEFF(cdataptr + npix - 3)
}
end
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