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//===========================================================================
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//
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// s_asinh.c
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//
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// Part of the standard mathematical function library
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//
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//===========================================================================
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// ####ECOSGPLCOPYRIGHTBEGIN####
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// -------------------------------------------
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// This file is part of eCos, the Embedded Configurable Operating System.
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// Copyright (C) 1998, 1999, 2000, 2001, 2002 Free Software Foundation, Inc.
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//
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// eCos is free software; you can redistribute it and/or modify it under
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// the terms of the GNU General Public License as published by the Free
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// Software Foundation; either version 2 or (at your option) any later
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// version.
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//
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// eCos is distributed in the hope that it will be useful, but WITHOUT
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// ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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// FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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// for more details.
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//
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// You should have received a copy of the GNU General Public License
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// along with eCos; if not, write to the Free Software Foundation, Inc.,
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// 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
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//
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// As a special exception, if other files instantiate templates or use
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// macros or inline functions from this file, or you compile this file
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// and link it with other works to produce a work based on this file,
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// this file does not by itself cause the resulting work to be covered by
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// the GNU General Public License. However the source code for this file
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// must still be made available in accordance with section (3) of the GNU
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// General Public License v2.
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//
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// This exception does not invalidate any other reasons why a work based
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// on this file might be covered by the GNU General Public License.
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// -------------------------------------------
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// ####ECOSGPLCOPYRIGHTEND####
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//===========================================================================
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//#####DESCRIPTIONBEGIN####
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//
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// Author(s): jlarmour
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// Contributors: jlarmour
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// Date: 1998-02-13
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// Purpose:
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// Description:
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// Usage:
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//
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//####DESCRIPTIONEND####
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//
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//===========================================================================
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// CONFIGURATION
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#include <pkgconf/libm.h> // Configuration header
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// Include the Math library?
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#ifdef CYGPKG_LIBM
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// Derived from code with the following copyright
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/* @(#)s_asinh.c 1.3 95/01/18 */
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/*
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* ====================================================
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* Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
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*
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* Developed at SunSoft, a Sun Microsystems, Inc. business.
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* Permission to use, copy, modify, and distribute this
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* software is freely granted, provided that this notice
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* is preserved.
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* ====================================================
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*/
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/* asinh(x)
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* Method :
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* Based on
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* asinh(x) = sign(x) * log [ |x| + sqrt(x*x+1) ]
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* we have
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* asinh(x) := x if 1+x*x=1,
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* := sign(x)*(log(x)+ln2)) for large |x|, else
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* := sign(x)*log(2|x|+1/(|x|+sqrt(x*x+1))) if|x|>2, else
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* := sign(x)*log1p(|x| + x^2/(1 + sqrt(1+x^2)))
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*/
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#include "mathincl/fdlibm.h"
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static const double
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one = 1.00000000000000000000e+00, /* 0x3FF00000, 0x00000000 */
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ln2 = 6.93147180559945286227e-01, /* 0x3FE62E42, 0xFEFA39EF */
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huge= 1.00000000000000000000e+300;
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double asinh(double x)
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{
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double t,w;
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int hx,ix;
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hx = CYG_LIBM_HI(x);
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ix = hx&0x7fffffff;
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if(ix>=0x7ff00000) return x+x; /* x is inf or NaN */
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if(ix< 0x3e300000) { /* |x|<2**-28 */
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if(huge+x>one) return x; /* return x inexact except 0 */
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}
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if(ix>0x41b00000) { /* |x| > 2**28 */
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w = __ieee754_log(fabs(x))+ln2;
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} else if (ix>0x40000000) { /* 2**28 > |x| > 2.0 */
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t = fabs(x);
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w = __ieee754_log(2.0*t+one/(sqrt(x*x+one)+t));
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} else { /* 2.0 > |x| > 2**-28 */
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t = x*x;
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w =log1p(fabs(x)+t/(one+sqrt(one+t)));
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}
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if(hx>0) return w; else return -w;
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}
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#endif // ifdef CYGPKG_LIBM
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// EOF s_asinh.c
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