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/* e_acoshf.c -- float version of e_acosh.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 |
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one = 1.0, |
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ln2 = 6.9314718246e-01; /* 0x3f317218 */ |
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float |
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acoshf(float x) |
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{ |
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float t; |
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int32_t hx; |
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GET_FLOAT_WORD(hx,x); |
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if(hx<0x3f800000) { /* x < 1 */ |
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return (x-x)/(x-x); |
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} else if(hx >=0x4d800000) { /* x > 2**28 */ |
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if(hx >=0x7f800000) { /* x is inf of NaN */ |
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return x+x; |
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} else |
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return logf(x)+ln2; /* acosh(huge)=log(2x) */ |
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} else if (hx==0x3f800000) { |
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return 0.0; /* acosh(1) = 0 */ |
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} else if (hx > 0x40000000) { /* 2**28 > x > 2 */ |
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t=x*x; |
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return logf((float)2.0*x-one/(x+sqrtf(t-one))); |
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} else { /* 1<x<2 */ |
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t = x-one; |
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return log1pf(t+sqrtf((float)2.0*t+t*t)); |
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} |
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} |