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# Copyright(c) 1986 Association of Universities for Research in Astronomy Inc.
# AFFTRR -- Forward fourier transform (real transform, real output arrays).
# The forward transform of the real array SR length NPIX is computed and
# returned in the real arrays FR and FI of length NPIX/2+1. Since the real
# transform is being performed the array SI is ignored and may be omitted.
# The transformation may be performed in place if desired. NPIX must be a
# power of 2.
procedure afftrr (sr, si, fr, fi, npix)
real sr[ARB], si[ARB] # spatial data (input). SI NOT USED.
real fr[ARB], fi[ARB] # real and imag parts of transform (output)
int npix
int ier
pointer sp, work
begin
call smark (sp)
call salloc (work, npix + 2, TY_REAL)
# Copy the real data vector into the work array.
call amovr (sr, Memr[work], npix)
# Compute the forward transform.
call ffa (Memr[work], npix, ier)
if (ier == 1)
call fatal (1, "afftrr: npix not a power of 2")
# Unpack the real and imaginary parts into the output arrays.
call aupxr (Memr[work], fr, fi, npix / 2 + 1)
call sfree (sp)
end
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