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+# Copyright(c) 1986 Association of Universities for Research in Astronomy Inc.
+
+# AFFTXR -- Forward fourier transform (complex transform, real arrays).
+# The fourier transform of the real arrays SR and SI containing complex data
+# pairs is computed and the complex transform coefficients are returned in
+# the real arrays FR and FI.  The transformation may be performed in place if
+# desired.  NPIX must be a power of 2.
+
+procedure afftxr (sr, si, fr, fi, npix)
+
+real	sr[ARB], si[ARB]	# data, spatial domain (input)
+real	fr[ARB], fi[ARB]	# transform, frequency domain (output)
+int	npix
+int	ier
+
+begin
+	# The following are no-ops if the transform is being performed
+	# in place.
+
+	call amovr (sr, fr, npix)
+	call amovr (si, fi, npix)
+
+	# Compute the forward transform.
+	call fft842 (0, npix, fr, fi, ier)
+	if (ier == 1)
+	    call fatal (1, "afftxr: npix not a power of 2")
+end