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include <imhdr.h>
include <math/curfit.h>
# Interpolation mode
define SI_LINEAR 1
define SI_CURVES 2
define SI_LEGENDRE 3
define SI_CHEBYSHEV 4
define SI_SPLINE3 5
define SI_SPLINE1 6
# T_SINTERP -- Interpolate for values in a table and optionally generate
# a spectral image
#
# A table of x,y pairs contained in a file is used to
# find interpolated values, y, for any other given independent
# variable, x. Extrapolation is performed if necessary.
#
# A series of values may be generated to generate a fine grid
# through a coarse sampling for purposes of plotting. This is
# done by setting the hidden parameter curve_gen to yes.
# The starting point, ending point, and sampling interval
# are also needed in this case (x1, x2, dx).
#
# If only a small number of values are needed to be interpolated
# from the table, the user may enter a number of x's from either
# a file or STDIN.
procedure t_sinterp()
real x, y, x1, x2, dx
int npts, i
int filelist, tbl, in
int user_mode, imlen, order, maxpts
char fname[SZ_FNAME], tbl_file[SZ_FNAME]
char image[SZ_FNAME]
char interp[SZ_LINE]
bool gen, make_image
pointer im, pix, sp, xtab, ytab, cv
int clpopni(), clgfil(), open(), fscan(), nscan()
int clgeti(), clgwrd()
real clgetr()
bool clgetb()
pointer immap(), impl1r()
begin
# Initialize interpolator
call intrp0 (1)
cv = NULL
# File containing x,y pairs in a table
call clgstr ("tbl_file", tbl_file, SZ_FNAME)
# Open table file and read as many points as possible
tbl = open (tbl_file, READ_ONLY, TEXT_FILE)
npts = 0
maxpts = clgeti ("tbl_size")
call smark (sp)
call salloc (xtab, maxpts, TY_REAL)
call salloc (ytab, maxpts, TY_REAL)
while (fscan(tbl) != EOF) {
npts = npts + 1
if (npts > maxpts)
call error (1, "Maximum table size exceeded.")
call gargr (Memr[xtab+npts-1])
call gargr (Memr[ytab+npts-1])
if (nscan() < 2) {
# call eprintf ("Error reading x,y pairs\n")
npts = npts - 1
}
}
call close (tbl)
if (npts < 1)
call error (1, "Table has no entries.")
# Linear, spline, or CURFIT option interpolator?
user_mode = clgwrd ("interp_mode", interp, SZ_LINE,
",linear,curves,legendre,chebyshev,spline3,spline1")
if (user_mode > 2 && user_mode <= 6)
order = clgeti ("order")
# Generate a curve?
gen = clgetb ("curve_gen")
# Or an image?
make_image = clgetb ("make_image")
if (gen || make_image) {
x1 = clgetr ("x1")
x2 = clgetr ("x2")
dx = clgetr ("dx")
imlen = clgeti ("npts")
# The above four variables overdefine the function
# One (other than x1) must be 0.0 --> solve for it
if (x2 == 0.0)
x2 = x1 + (imlen-1) * dx
else if (dx == 0.0)
dx = (x2 - x1) / (imlen - 1)
imlen = nint ((x2 - x1) / dx + 1)
# Verify that dx will not cause an infinite loop
if (dx == 0.0 || dx * (x2-x1) < 0.0)
call error (1, "Interval paramater dx implies infinite loop.")
if (make_image) {
call clgstr ("image", image, SZ_FNAME)
im = immap (image, NEW_IMAGE, 0)
IM_NDIM (im) = 1
IM_LEN (im, 1) = imlen
IM_PIXTYPE (im) = TY_REAL
pix = impl1r (im)
do i = 1, imlen {
x = x1 + (i - 1) * dx
call gen_pixel (Memr[xtab], Memr[ytab], npts,
user_mode, order, x, y, cv)
Memr[pix+i-1] = y
}
call imaddr (im, "CRVAL1", x1)
call imaddr (im, "CDELT1", dx)
call imaddr (im, "CD1_1", dx)
call imaddr (im, "CRPIX1", 1.)
call imaddi (im, "DC-FLAG", 0)
call imunmap (im)
} else {
do i = 1, imlen {
x = x1 + (i - 1) * dx
call gen_pixel (Memr[xtab], Memr[ytab], npts,
user_mode, order, x, y, cv)
call printf ("%12.5g %12.5g\n")
call pargr (x)
call pargr (y)
}
call flush (STDOUT)
}
# No, just one point at a time
} else {
# Open input list
filelist = clpopni ("input")
while (clgfil (filelist, fname, SZ_FNAME) != EOF) {
in = open (fname, READ_ONLY, TEXT_FILE)
# Process input requests
while (fscan(in) != EOF) {
call gargr (x)
call gen_pixel (Memr[xtab], Memr[ytab], npts,
user_mode, order, x, y, cv)
call printf ("%12.5g %12.5g\n")
call pargr (x)
call pargr (y)
call flush (STDOUT)
}
call close (in)
}
call clpcls (filelist)
}
call cvfree (cv)
call sfree (sp)
end
# GEN_PIXEL -- Generate a pixel value using specified interpolator
procedure gen_pixel (xtab, ytab, npts, mode, order, x, y, cv)
real xtab[ARB], ytab[ARB]
int npts
real x
int mode, order
real y
pointer cv
int fit, ier
pointer wt, sp
real cveval()
begin
# Interpolate after selecting option
switch (mode) {
case SI_LINEAR:
call lintrp (1, xtab, ytab, npts, x, y, ier)
case SI_CURVES:
call intrp (1, xtab, ytab, npts, x, y, ier)
default:
if (cv == NULL) {
call smark (sp)
call salloc (wt, npts, TY_REAL)
call amovkr (1.0, Memr[wt], npts)
switch (mode) {
case SI_LEGENDRE:
fit = LEGENDRE
case SI_CHEBYSHEV:
fit = CHEBYSHEV
case SI_SPLINE3:
fit = SPLINE3
case SI_SPLINE1:
fit = SPLINE1
default:
fit = SPLINE1
}
call cvinit (cv, fit, order, xtab[1], xtab[npts])
call cvfit (cv, xtab, ytab, Memr[wt], npts, WTS_UNIFORM,
ier)
call sfree (sp)
}
y = cveval (cv, x)
}
end
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