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/* e_atanhf.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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#include "math.h" |
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#include "math_private.h" |
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static const float one = 1.0, huge = 1e30; |
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static const float zero = 0.0; |
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float |
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atanhf(float x) |
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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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} |