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diff --git a/sysdeps/libm-ieee754/s_cprojf.c b/sysdeps/libm-ieee754/s_cprojf.c
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+/* Compute projection of complex float value to Riemann sphere.
+ Copyright (C) 1997 Free Software Foundation, Inc.
+ This file is part of the GNU C Library.
+ Contributed by Ulrich Drepper <drepper@cygnus.com>, 1997.
+
+ The GNU C Library is free software; you can redistribute it and/or
+ modify it under the terms of the GNU Library General Public License as
+ published by the Free Software Foundation; either version 2 of the
+ License, or (at your option) any later version.
+
+ The GNU C Library is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ Library General Public License for more details.
+
+ You should have received a copy of the GNU Library General Public
+ License along with the GNU C Library; see the file COPYING.LIB. If not,
+ write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ Boston, MA 02111-1307, USA. */
+
+#include <complex.h>
+#include <math.h>
+
+
+__complex__ float
+__cprojf (__complex__ float x)
+{
+ __complex__ float res;
+
+ if (!finite (__real__ x) || !finite (__imag__ x))
+ {
+ __real__ res = INFINITY;
+ __imag__ res = __copysignf (0.0, __imag__ x);
+ }
+ else
+ {
+ float den = __real__ x * __real__ x + __imag__ x * __imag__ x + 1.0;
+
+ __real__ res = (2.0 * __real__ x) / den;
+ __imag__ res = (2.0 * __imag__ x) / den;
+ }
+
+ return res;
+}
+weak_alias (__cprojf, cprojf)