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git-svn-id: http://svn.freeswitch.org/svn/freeswitch/trunk@3693 d0543943-73ff-0310-b7d9-9358b9ac24b2
102 lines
3.4 KiB
C
102 lines
3.4 KiB
C
/* -*- Mode: C; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
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*
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* ***** BEGIN LICENSE BLOCK *****
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* Version: MPL 1.1/GPL 2.0/LGPL 2.1
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*
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* The contents of this file are subject to the Mozilla Public License Version
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* 1.1 (the "License"); you may not use this file except in compliance with
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* the License. You may obtain a copy of the License at
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* http://www.mozilla.org/MPL/
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*
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* Software distributed under the License is distributed on an "AS IS" basis,
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* WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
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* for the specific language governing rights and limitations under the
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* License.
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*
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* The Original Code is Mozilla Communicator client code, released
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* March 31, 1998.
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*
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* The Initial Developer of the Original Code is
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* Sun Microsystems, Inc.
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* Portions created by the Initial Developer are Copyright (C) 1998
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* the Initial Developer. All Rights Reserved.
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*
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* Contributor(s):
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*
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* Alternatively, the contents of this file may be used under the terms of
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* either of the GNU General Public License Version 2 or later (the "GPL"),
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* or the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
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* in which case the provisions of the GPL or the LGPL are applicable instead
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* of those above. If you wish to allow use of your version of this file only
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* under the terms of either the GPL or the LGPL, and not to allow others to
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* use your version of this file under the terms of the MPL, indicate your
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* decision by deleting the provisions above and replace them with the notice
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* and other provisions required by the GPL or the LGPL. If you do not delete
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* the provisions above, a recipient may use your version of this file under
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* the terms of any one of the MPL, the GPL or the LGPL.
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*
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* ***** END LICENSE BLOCK ***** */
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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 "fdlibm.h"
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#ifdef __STDC__
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static const double
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#else
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static double
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#endif
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one = 1.00000000000000000000e+00, /* 0x3FF00000, 0x00000000 */
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ln2 = 6.93147180559945286227e-01, /* 0x3FE62E42, 0xFEFA39EF */
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really_big= 1.00000000000000000000e+300;
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#ifdef __STDC__
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double fd_asinh(double x)
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#else
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double fd_asinh(x)
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double x;
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#endif
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{
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fd_twoints u;
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double t,w;
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int hx,ix;
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u.d = x;
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hx = __HI(u);
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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(really_big+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(fd_fabs(x))+ln2;
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} else if (ix>0x40000000) { /* 2**28 > |x| > 2.0 */
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t = fd_fabs(x);
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w = __ieee754_log(2.0*t+one/(fd_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 =fd_log1p(fd_fabs(x)+t/(one+fd_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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