12116Sjkh/* e_coshf.c -- float version of e_cosh.c.
22116Sjkh * Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com.
32116Sjkh */
42116Sjkh
52116Sjkh/*
62116Sjkh * ====================================================
72116Sjkh * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
82116Sjkh *
92116Sjkh * Developed at SunPro, a Sun Microsystems, Inc. business.
102116Sjkh * Permission to use, copy, modify, and distribute this
118870Srgrimes * software is freely granted, provided that this notice
122116Sjkh * is preserved.
132116Sjkh * ====================================================
142116Sjkh */
152116Sjkh
16176451Sdas#include <sys/cdefs.h>
17176451Sdas__FBSDID("$FreeBSD$");
182116Sjkh
192116Sjkh#include "math.h"
202116Sjkh#include "math_private.h"
212116Sjkh
222116Sjkhstatic const float one = 1.0, half=0.5, huge = 1.0e30;
232116Sjkh
2497407Salfredfloat
2597407Salfred__ieee754_coshf(float x)
268870Srgrimes{
272116Sjkh	float t,w;
282116Sjkh	int32_t ix;
292116Sjkh
302116Sjkh	GET_FLOAT_WORD(ix,x);
312116Sjkh	ix &= 0x7fffffff;
322116Sjkh
332116Sjkh    /* x is INF or NaN */
348870Srgrimes	if(ix>=0x7f800000) return x*x;
352116Sjkh
362116Sjkh    /* |x| in [0,0.5*ln2], return 1+expm1(|x|)^2/(2*exp(|x|)) */
372116Sjkh	if(ix<0x3eb17218) {
382116Sjkh	    t = expm1f(fabsf(x));
392116Sjkh	    w = one+t;
40152352Sbde	    if (ix<0x39800000) return one;	/* cosh(tiny) = 1 */
412116Sjkh	    return one+(t*t)/(w+w);
422116Sjkh	}
432116Sjkh
44152352Sbde    /* |x| in [0.5*ln2,9], return (exp(|x|)+1/exp(|x|))/2; */
45152352Sbde	if (ix < 0x41100000) {
462116Sjkh		t = __ieee754_expf(fabsf(x));
472116Sjkh		return half*t+half/t;
482116Sjkh	}
492116Sjkh
50152352Sbde    /* |x| in [9, log(maxfloat)] return half*exp(|x|) */
51152352Sbde	if (ix < 0x42b17217)  return half*__ieee754_expf(fabsf(x));
522116Sjkh
53152352Sbde    /* |x| in [log(maxfloat), overflowthresold] */
54226598Sdas	if (ix<=0x42b2d4fc)
55226598Sdas	    return __ldexp_expf(fabsf(x), -1);
562116Sjkh
572116Sjkh    /* |x| > overflowthresold, cosh(x) overflow */
582116Sjkh	return huge*huge;
592116Sjkh}
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