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/* e_coshf.c -- float version of e_cosh.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 volatile float huge = 1.0e30; |
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static const float one = 1.0, half=0.5; |
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float |
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coshf(float x) |
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{ |
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float t,w; |
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int32_t ix; |
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GET_FLOAT_WORD(ix,x); |
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ix &= 0x7fffffff; |
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/* x is INF or NaN */ |
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if(ix>=0x7f800000) return x*x; |
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/* |x| in [0,0.5*ln2], return 1+expm1(|x|)^2/(2*exp(|x|)) */ |
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if(ix<0x3eb17218) { |
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t = expm1f(fabsf(x)); |
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w = one+t; |
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if (ix<0x24000000) return w; /* cosh(tiny) = 1 */ |
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return one+(t*t)/(w+w); |
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} |
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/* |x| in [0.5*ln2,22], return (exp(|x|)+1/exp(|x|)/2; */ |
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if (ix < 0x41b00000) { |
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t = expf(fabsf(x)); |
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return half*t+half/t; |
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} |
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/* |x| in [22, log(maxdouble)] return half*exp(|x|) */ |
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if (ix < 0x42b17180) return half*expf(fabsf(x)); |
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/* |x| in [log(maxdouble), overflowthresold] */ |
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if (ix<=0x42b2d4fc) { |
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w = expf(half*fabsf(x)); |
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t = half*w; |
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return t*w; |
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} |
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/* |x| > overflowthresold, cosh(x) overflow */ |
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return huge*huge; |
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} |
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DEF_STD(coshf); |