0,0 → 1,90 |
/* Copyright (C) 1994 DJ Delorie, see COPYING.DJ for details */ |
/* e_acosf.c -- float version of e_acos.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_acosf.c,v 1.2 1994/08/18 23:04:53 jtc Exp $"; |
#endif |
|
#include "math.h" |
#include "math_private.h" |
|
#ifdef __STDC__ |
static const float |
#else |
static float |
#endif |
one = 1.0000000000e+00, /* 0x3F800000 */ |
pi = 3.1415925026e+00, /* 0x40490fda */ |
pio2_hi = 1.5707962513e+00, /* 0x3fc90fda */ |
pio2_lo = 7.5497894159e-08, /* 0x33a22168 */ |
pS0 = 1.6666667163e-01, /* 0x3e2aaaab */ |
pS1 = -3.2556581497e-01, /* 0xbea6b090 */ |
pS2 = 2.0121252537e-01, /* 0x3e4e0aa8 */ |
pS3 = -4.0055535734e-02, /* 0xbd241146 */ |
pS4 = 7.9153501429e-04, /* 0x3a4f7f04 */ |
pS5 = 3.4793309169e-05, /* 0x3811ef08 */ |
qS1 = -2.4033949375e+00, /* 0xc019d139 */ |
qS2 = 2.0209457874e+00, /* 0x4001572d */ |
qS3 = -6.8828397989e-01, /* 0xbf303361 */ |
qS4 = 7.7038154006e-02; /* 0x3d9dc62e */ |
|
#ifdef __STDC__ |
float __ieee754_acosf(float x) |
#else |
float __ieee754_acosf(x) |
float x; |
#endif |
{ |
float z,p,q,r,w,s,c,df; |
int32_t hx,ix; |
GET_FLOAT_WORD(hx,x); |
ix = hx&0x7fffffff; |
if(ix==0x3f800000) { /* |x|==1 */ |
if(hx>0) return 0.0; /* acos(1) = 0 */ |
else return pi+(float)2.0*pio2_lo; /* acos(-1)= pi */ |
} else if(ix>0x3f800000) { /* |x| >= 1 */ |
return (x-x)/(x-x); /* acos(|x|>1) is NaN */ |
} |
if(ix<0x3f000000) { /* |x| < 0.5 */ |
if(ix<=0x23000000) return pio2_hi+pio2_lo;/*if|x|<2**-57*/ |
z = x*x; |
p = z*(pS0+z*(pS1+z*(pS2+z*(pS3+z*(pS4+z*pS5))))); |
q = one+z*(qS1+z*(qS2+z*(qS3+z*qS4))); |
r = p/q; |
return pio2_hi - (x - (pio2_lo-x*r)); |
} else if (hx<0) { /* x < -0.5 */ |
z = (one+x)*(float)0.5; |
p = z*(pS0+z*(pS1+z*(pS2+z*(pS3+z*(pS4+z*pS5))))); |
q = one+z*(qS1+z*(qS2+z*(qS3+z*qS4))); |
s = sqrtf(z); |
r = p/q; |
w = r*s-pio2_lo; |
return pi - (float)2.0*(s+w); |
} else { /* x > 0.5 */ |
int32_t idf; |
z = (one-x)*(float)0.5; |
s = sqrtf(z); |
df = s; |
GET_FLOAT_WORD(idf,df); |
SET_FLOAT_WORD(df,idf&0xfffff000); |
c = (z-df*df)/(s+df); |
p = z*(pS0+z*(pS1+z*(pS2+z*(pS3+z*(pS4+z*pS5))))); |
q = one+z*(qS1+z*(qS2+z*(qS3+z*qS4))); |
r = p/q; |
w = r*s+c; |
return (float)2.0*(df+w); |
} |
} |