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52 lines
1.6 KiB
C
52 lines
1.6 KiB
C
/* Compute projection of complex double value to Riemann sphere.
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Copyright (C) 1997, 1999 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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Contributed by Ulrich Drepper <drepper@cygnus.com>, 1997.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Library General Public License as
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published by the Free Software Foundation; either version 2 of the
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License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Library General Public License for more details.
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You should have received a copy of the GNU Library General Public
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License along with the GNU C Library; see the file COPYING.LIB. If not,
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write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
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Boston, MA 02111-1307, USA. */
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#include <complex.h>
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#include <math.h>
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__complex__ double
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__cproj (__complex__ double x)
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{
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__complex__ double res;
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if (isnan (__real__ x) && isnan (__imag__ x))
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return x;
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else if (!isfinite (__real__ x) || !isfinite (__imag__ x))
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{
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__real__ res = INFINITY;
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__imag__ res = __copysign (0.0, __imag__ x);
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}
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else
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{
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double den = __real__ x * __real__ x + __imag__ x * __imag__ x + 1.0;
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__real__ res = (2.0 * __real__ x) / den;
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__imag__ res = (2.0 * __imag__ x) / den;
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}
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return res;
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}
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weak_alias (__cproj, cproj)
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#ifdef NO_LONG_DOUBLE
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strong_alias (__cproj, __cprojl)
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weak_alias (__cproj, cprojl)
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#endif
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