mirror of
https://github.com/autc04/Retro68.git
synced 2024-12-11 03:52:59 +00:00
54 lines
1.3 KiB
C
54 lines
1.3 KiB
C
/* ef_acosh.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.
|
|
* ====================================================
|
|
*
|
|
*/
|
|
|
|
#include "fdlibm.h"
|
|
|
|
#ifdef __STDC__
|
|
static const float
|
|
#else
|
|
static float
|
|
#endif
|
|
one = 1.0,
|
|
ln2 = 6.9314718246e-01; /* 0x3f317218 */
|
|
|
|
#ifdef __STDC__
|
|
float acoshf(float x)
|
|
#else
|
|
float 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 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 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));
|
|
}
|
|
}
|