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73 lines
1.7 KiB
C
73 lines
1.7 KiB
C
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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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#if defined(LIBM_SCCS) && !defined(lint)
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static char rcsid[] = "$NetBSD: e_coshf.c,v 1.5 1995/05/10 20:45:01 jtc Exp $";
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#endif
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#include "math.h"
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#include "math_private.h"
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#ifdef __STDC__
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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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#else
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static float one = 1.0, half=0.5, huge = 1.0e30;
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#endif
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#ifdef __STDC__
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float __ieee754_coshf(float x)
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#else
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float __ieee754_coshf(x)
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float x;
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#endif
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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 = __ieee754_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*__ieee754_expf(fabsf(x));
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/* |x| in [log(maxdouble), overflowthresold] */
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if (ix<=0x42b2d4fc) {
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w = __ieee754_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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