12116Sjkh/* e_acoshf.c -- float version of e_acosh.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
228870Srgrimesstatic const float
232116Sjkhone	= 1.0,
242116Sjkhln2	= 6.9314718246e-01;  /* 0x3f317218 */
252116Sjkh
2697407Salfredfloat
2797407Salfred__ieee754_acoshf(float x)
288870Srgrimes{
292116Sjkh	float t;
302116Sjkh	int32_t hx;
312116Sjkh	GET_FLOAT_WORD(hx,x);
322116Sjkh	if(hx<0x3f800000) {		/* x < 1 */
332116Sjkh	    return (x-x)/(x-x);
342116Sjkh	} else if(hx >=0x4d800000) {	/* x > 2**28 */
352116Sjkh	    if(hx >=0x7f800000) {	/* x is inf of NaN */
362116Sjkh	        return x+x;
378870Srgrimes	    } else
382116Sjkh		return __ieee754_logf(x)+ln2;	/* acosh(huge)=log(2x) */
392116Sjkh	} else if (hx==0x3f800000) {
402116Sjkh	    return 0.0;			/* acosh(1) = 0 */
412116Sjkh	} else if (hx > 0x40000000) {	/* 2**28 > x > 2 */
422116Sjkh	    t=x*x;
4323579Sbde	    return __ieee754_logf((float)2.0*x-one/(x+__ieee754_sqrtf(t-one)));
442116Sjkh	} else {			/* 1<x<2 */
452116Sjkh	    t = x-one;
4623579Sbde	    return log1pf(t+__ieee754_sqrtf((float)2.0*t+t*t));
472116Sjkh	}
482116Sjkh}
49