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+# Copyright(c) 1986 Association of Universities for Research in Astronomy Inc.
+
+# AFFTXX -- Forward fourier transform (complex transform, complex data).
+# The fourier transform of the complex array A of length NPIX pixels is
+# computed and the NPIX complex transform coefficients are returned in the
+# complex array B.  The transformation may be performed in place if desired.
+# NPIX must be a power of 2.
+
+procedure afftxx (a, b, npix)
+
+complex	a[ARB]			# data (input)
+complex	b[ARB]			# transform (output)
+int	npix
+
+int	ier
+pointer	sp, xr, xi
+
+begin
+	call smark (sp)
+	call salloc (xr, npix, TY_REAL)
+	call salloc (xi, npix, TY_REAL)
+
+	# Rearrange the elements of the A array as required by FFT842.
+	# Convert the array A of complex values into an array of reals
+	# and an array of imaginaries.
+
+	call aupxr (a, Memr[xr], Memr[xi], npix)
+
+	# Compute the forward transform.
+	call fft842 (0, npix, Memr[xr], Memr[xi], ier)
+	if (ier == 1)
+	    call fatal (1, "afftxx: npix not a power of 2")
+
+	# Repack the real and imaginary arrays to form the complex output
+	# array.
+	call apkxr (Memr[xr], Memr[xi], b, npix)
+
+	call sfree (sp)
+end