55 lines
1.2 KiB
C
55 lines
1.2 KiB
C
/* ef_atanh.c -- float version of e_atanh.c.
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* Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com.
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*/
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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 SunPro, 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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#include "fdlibm.h"
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#ifdef __STDC__
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static const float one = 1.0, huge = 1e30;
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#else
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static float one = 1.0, huge = 1e30;
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#endif
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#ifdef __STDC__
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static const float zero = 0.0;
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#else
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static float zero = 0.0;
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#endif
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#ifdef __STDC__
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float atanhf(float x)
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#else
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float atanhf(x)
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float x;
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#endif
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{
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float t;
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__int32_t hx,ix;
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GET_FLOAT_WORD(hx,x);
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ix = hx&0x7fffffff;
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if (ix>0x3f800000) /* |x|>1 */
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return (x-x)/(x-x);
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if(ix==0x3f800000)
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return x/zero;
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if(ix<0x31800000&&(huge+x)>zero) return x; /* x<2**-28 */
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SET_FLOAT_WORD(x,ix);
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if(ix<0x3f000000) { /* x < 0.5 */
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t = x+x;
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t = (float)0.5*log1pf(t+t*x/(one-x));
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} else
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t = (float)0.5*log1pf((x+x)/(one-x));
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if(hx>=0) return t; else return -t;
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}
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