-/* origin: FreeBSD /usr/src/lib/msun/src/e_coshf.c */
-/*
- * Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com.
- */
-/*
- * ====================================================
- * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
- *
- * Developed at SunPro, a Sun Microsystems, Inc. business.
- * Permission to use, copy, modify, and distribute this
- * software is freely granted, provided that this notice
- * is preserved.
- * ====================================================
- */
-
#include "libm.h"
-static const float one = 1.0, half = 0.5, huge = 1.0e30;
-
float coshf(float x)
{
- float t, w;
- int32_t ix;
-
- GET_FLOAT_WORD(ix, x);
- ix &= 0x7fffffff;
-
- /* x is INF or NaN */
- if (ix >= 0x7f800000)
- return x*x;
-
- /* |x| in [0,0.5*ln2], return 1+expm1(|x|)^2/(2*exp(|x|)) */
- if (ix < 0x3eb17218) {
- t = expm1f(fabsf(x));
- w = one+t;
- if (ix<0x39800000)
- return one; /* cosh(tiny) = 1 */
- return one + (t*t)/(w+w);
+ union {float f; uint32_t i;} u = {.f = x};
+ uint32_t w;
+ float t;
+
+ /* |x| */
+ u.i &= 0x7fffffff;
+ x = u.f;
+ w = u.i;
+
+ /* |x| < log(2) */
+ if (w < 0x3f317217) {
+ if (w < 0x3f800000 - (12<<23)) {
+ FORCE_EVAL(x + 0x1p120f);
+ return 1;
+ }
+ t = expm1f(x);
+ return 1 + t*t/(2*(1+t));
}
- /* |x| in [0.5*ln2,9], return (exp(|x|)+1/exp(|x|))/2; */
- if (ix < 0x41100000) {
- t = expf(fabsf(x));
- return half*t + half/t;
+ /* |x| < log(FLT_MAX) */
+ if (w < 0x42b17217) {
+ t = expf(x);
+ return 0.5f*(t + 1/t);
}
- /* |x| in [9, log(maxfloat)] return half*exp(|x|) */
- if (ix < 0x42b17217)
- return half*expf(fabsf(x));
-
- /* |x| in [log(maxfloat), overflowthresold] */
- if (ix <= 0x42b2d4fc)
- return __expo2f(fabsf(x));
-
- /* |x| > overflowthresold, cosh(x) overflow */
- return huge*huge;
+ /* |x| > log(FLT_MAX) or nan */
+ t = __expo2f(x, 1.0f);
+ return t;
}