| 0,0 → 1,58 |
|---|
| /* Copyright (C) 1994 DJ Delorie, see COPYING.DJ for details */ |
| /* e_acoshf.c -- float version of e_acosh.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. |
| * ==================================================== |
| */ |
| |
| #if defined(LIBM_SCCS) && !defined(lint) |
| static char rcsid[] = "$Id: e_acoshf.c,v 1.2 1994/08/18 23:04:57 jtc Exp $"; |
| #endif |
| |
| #include "math.h" |
| #include "math_private.h" |
| |
| #ifdef __STDC__ |
| static const float |
| #else |
| static float |
| #endif |
| one = 1.0, |
| ln2 = 6.9314718246e-01; /* 0x3f317218 */ |
| |
| #ifdef __STDC__ |
| float __ieee754_acoshf(float x) |
| #else |
| float __ieee754_acoshf(x) |
| float x; |
| #endif |
| { |
| float t; |
| int32_t hx; |
| GET_FLOAT_WORD(hx,x); |
| if(hx<0x3f800000) { /* x < 1 */ |
| return (x-x)/(x-x); |
| } else if(hx >=0x4d800000) { /* x > 2**28 */ |
| if(hx >=0x7f800000) { /* x is inf of NaN */ |
| return x+x; |
| } else |
| return __ieee754_logf(x)+ln2; /* acosh(huge)=log(2x) */ |
| } else if (hx==0x3f800000) { |
| return 0.0; /* acosh(1) = 0 */ |
| } else if (hx > 0x40000000) { /* 2**28 > x > 2 */ |
| t=x*x; |
| return __ieee754_logf((float)2.0*x-one/(x+sqrtf(t-one))); |
| } else { /* 1<x<2 */ |
| t = x-one; |
| return log1pf(t+sqrtf((float)2.0*t+t*t)); |
| } |
| } |