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/* * Mode: C; tabwidth: 8; indenttabsmode: nil; cbasicoffset: 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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/* @(#)e_atanh.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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*/ 
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/* __ieee754_atanh(x) 
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* Method : 
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* 1.Reduced x to positive by atanh(x) = atanh(x) 
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* 2.For x>=0.5 
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* 1 2x x 
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* atanh(x) =  * log(1 + ) = 0.5 * log1p(2 * ) 
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* 2 1  x 1  x 
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* 
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* For x<0.5 
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* atanh(x) = 0.5*log1p(2x+2x*x/(1x)) 
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* 
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* Special cases: 
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* atanh(x) is NaN if x > 1 with signal; 
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* atanh(NaN) is that NaN with no signal; 
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* atanh(+1) is +INF with signal. 
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* 
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*/ 
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#include "fdlibm.h" 
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#ifdef __STDC__ 
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static const double one = 1.0, really_big = 1e300; 
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#else 
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static double one = 1.0, really_big = 1e300; 
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#endif 
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static double zero = 0.0; 
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#ifdef __STDC__ 
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double __ieee754_atanh(double x) 
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#else 
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double __ieee754_atanh(x) 
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double x; 
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#endif 
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{ 
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double t; 
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int hx,ix; 
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unsigned lx; 
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fd_twoints u; 
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u.d = x; 
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hx = __HI(u); /* high word */ 
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lx = __LO(u); /* low word */ 
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ix = hx&0x7fffffff; 
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if ((ix((lx((int)lx))>>31))>0x3ff00000) /* x>1 */ 
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return (xx)/(xx); 
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if(ix==0x3ff00000) 
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return x/zero; 
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if(ix<0x3e300000&&(really_big+x)>zero) return x; /* x<2**28 */ 
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u.d = x; 
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__HI(u) = ix; /* x < x */ 
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x = u.d; 
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if(ix<0x3fe00000) { /* x < 0.5 */ 
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t = x+x; 
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t = 0.5*fd_log1p(t+t*x/(onex)); 
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} else 
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t = 0.5*fd_log1p((x+x)/(onex)); 
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if(hx>=0) return t; else return t; 
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} 