1 /* e_acoshf.c -- float version of e_acosh.c. 2 * Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com. 3 */ 4 5 /* 6 * ==================================================== 7 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved. 8 * 9 * Developed at SunPro, a Sun Microsystems, Inc. business. 10 * Permission to use, copy, modify, and distribute this 11 * software is freely granted, provided that this notice 12 * is preserved. 13 * ==================================================== 14 */ 15 16 #include "cdefs-compat.h" 17 //__FBSDID("$FreeBSD: src/lib/msun/src/e_acoshf.c,v 1.8 2008/02/22 02:30:34 das Exp $"); 18 19 #include "openlibm.h" 20 #include "math_private.h" 21 22 static const float 23 one = 1.0, 24 ln2 = 6.9314718246e-01; /* 0x3f317218 */ 25 26 DLLEXPORT float 27 __ieee754_acoshf(float x) 28 { 29 float t; 30 int32_t hx; 31 GET_FLOAT_WORD(hx,x); 32 if(hx<0x3f800000) { /* x < 1 */ 33 return (x-x)/(x-x); 34 } else if(hx >=0x4d800000) { /* x > 2**28 */ 35 if(hx >=0x7f800000) { /* x is inf of NaN */ 36 return x+x; 37 } else 38 return __ieee754_logf(x)+ln2; /* acosh(huge)=log(2x) */ 39 } else if (hx==0x3f800000) { 40 return 0.0; /* acosh(1) = 0 */ 41 } else if (hx > 0x40000000) { /* 2**28 > x > 2 */ 42 t=x*x; 43 return __ieee754_logf((float)2.0*x-one/(x+__ieee754_sqrtf(t-one))); 44 } else { /* 1<x<2 */ 45 t = x-one; 46 return log1pf(t+__ieee754_sqrtf((float)2.0*t+t*t)); 47 } 48 } 49