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-rw-r--r--src/math/e_cosh.c82
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diff --git a/src/math/e_cosh.c b/src/math/e_cosh.c
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--- a/src/math/e_cosh.c
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-
-/* @(#)e_cosh.c 1.3 95/01/18 */
-/*
- * ====================================================
- * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
- *
- * Developed at SunSoft, a Sun Microsystems, Inc. business.
- * Permission to use, copy, modify, and distribute this
- * software is freely granted, provided that this notice
- * is preserved.
- * ====================================================
- */
-
-/* cosh(x)
- * Method :
- * mathematically cosh(x) if defined to be (exp(x)+exp(-x))/2
- * 1. Replace x by |x| (cosh(x) = cosh(-x)).
- * 2.
- * [ exp(x) - 1 ]^2
- * 0 <= x <= ln2/2 : cosh(x) := 1 + -------------------
- * 2*exp(x)
- *
- * exp(x) + 1/exp(x)
- * ln2/2 <= x <= 22 : cosh(x) := -------------------
- * 2
- * 22 <= x <= lnovft : cosh(x) := exp(x)/2
- * lnovft <= x <= ln2ovft: cosh(x) := exp(x/2)/2 * exp(x/2)
- * ln2ovft < x : cosh(x) := huge*huge (overflow)
- *
- * Special cases:
- * cosh(x) is |x| if x is +INF, -INF, or NaN.
- * only cosh(0)=1 is exact for finite x.
- */
-
-#include <math.h>
-#include "math_private.h"
-
-static const double one = 1.0, half=0.5, huge = 1.0e300;
-
-double
-cosh(double x)
-{
- double t,w;
- int32_t ix;
- uint32_t lx;
-
- /* High word of |x|. */
- GET_HIGH_WORD(ix,x);
- ix &= 0x7fffffff;
-
- /* x is INF or NaN */
- if(ix>=0x7ff00000) return x*x;
-
- /* |x| in [0,0.5*ln2], return 1+expm1(|x|)^2/(2*exp(|x|)) */
- if(ix<0x3fd62e43) {
- t = expm1(fabs(x));
- w = one+t;
- if (ix<0x3c800000) return w; /* cosh(tiny) = 1 */
- return one+(t*t)/(w+w);
- }
-
- /* |x| in [0.5*ln2,22], return (exp(|x|)+1/exp(|x|)/2; */
- if (ix < 0x40360000) {
- t = exp(fabs(x));
- return half*t+half/t;
- }
-
- /* |x| in [22, log(maxdouble)] return half*exp(|x|) */
- if (ix < 0x40862E42) return half*exp(fabs(x));
-
- /* |x| in [log(maxdouble), overflowthresold] */
- GET_LOW_WORD(lx,x);
- if (ix<0x408633CE ||
- ((ix==0x408633ce)&&(lx<=(uint32_t)0x8fb9f87d))) {
- w = exp(half*fabs(x));
- t = half*w;
- return t*w;
- }
-
- /* |x| > overflowthresold, cosh(x) overflow */
- return huge*huge;
-}