/* ef_acos.c -- float version of e_acos.c.
|
/* ef_acos.c -- float version of e_acos.c.
|
* Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com.
|
* Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com.
|
*/
|
*/
|
|
|
/*
|
/*
|
* ====================================================
|
* ====================================================
|
* Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
|
* Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
|
*
|
*
|
* Developed at SunPro, a Sun Microsystems, Inc. business.
|
* Developed at SunPro, a Sun Microsystems, Inc. business.
|
* Permission to use, copy, modify, and distribute this
|
* Permission to use, copy, modify, and distribute this
|
* software is freely granted, provided that this notice
|
* software is freely granted, provided that this notice
|
* is preserved.
|
* is preserved.
|
* ====================================================
|
* ====================================================
|
*/
|
*/
|
|
|
#include "fdlibm.h"
|
#include "fdlibm.h"
|
|
|
#ifdef __STDC__
|
#ifdef __STDC__
|
static const float
|
static const float
|
#else
|
#else
|
static float
|
static float
|
#endif
|
#endif
|
one = 1.0000000000e+00, /* 0x3F800000 */
|
one = 1.0000000000e+00, /* 0x3F800000 */
|
pi = 3.1415925026e+00, /* 0x40490fda */
|
pi = 3.1415925026e+00, /* 0x40490fda */
|
pio2_hi = 1.5707962513e+00, /* 0x3fc90fda */
|
pio2_hi = 1.5707962513e+00, /* 0x3fc90fda */
|
pio2_lo = 7.5497894159e-08, /* 0x33a22168 */
|
pio2_lo = 7.5497894159e-08, /* 0x33a22168 */
|
pS0 = 1.6666667163e-01, /* 0x3e2aaaab */
|
pS0 = 1.6666667163e-01, /* 0x3e2aaaab */
|
pS1 = -3.2556581497e-01, /* 0xbea6b090 */
|
pS1 = -3.2556581497e-01, /* 0xbea6b090 */
|
pS2 = 2.0121252537e-01, /* 0x3e4e0aa8 */
|
pS2 = 2.0121252537e-01, /* 0x3e4e0aa8 */
|
pS3 = -4.0055535734e-02, /* 0xbd241146 */
|
pS3 = -4.0055535734e-02, /* 0xbd241146 */
|
pS4 = 7.9153501429e-04, /* 0x3a4f7f04 */
|
pS4 = 7.9153501429e-04, /* 0x3a4f7f04 */
|
pS5 = 3.4793309169e-05, /* 0x3811ef08 */
|
pS5 = 3.4793309169e-05, /* 0x3811ef08 */
|
qS1 = -2.4033949375e+00, /* 0xc019d139 */
|
qS1 = -2.4033949375e+00, /* 0xc019d139 */
|
qS2 = 2.0209457874e+00, /* 0x4001572d */
|
qS2 = 2.0209457874e+00, /* 0x4001572d */
|
qS3 = -6.8828397989e-01, /* 0xbf303361 */
|
qS3 = -6.8828397989e-01, /* 0xbf303361 */
|
qS4 = 7.7038154006e-02; /* 0x3d9dc62e */
|
qS4 = 7.7038154006e-02; /* 0x3d9dc62e */
|
|
|
#ifdef __STDC__
|
#ifdef __STDC__
|
float __ieee754_acosf(float x)
|
float __ieee754_acosf(float x)
|
#else
|
#else
|
float __ieee754_acosf(x)
|
float __ieee754_acosf(x)
|
float x;
|
float x;
|
#endif
|
#endif
|
{
|
{
|
float z,p,q,r,w,s,c,df;
|
float z,p,q,r,w,s,c,df;
|
__int32_t hx,ix;
|
__int32_t hx,ix;
|
GET_FLOAT_WORD(hx,x);
|
GET_FLOAT_WORD(hx,x);
|
ix = hx&0x7fffffff;
|
ix = hx&0x7fffffff;
|
if(ix==0x3f800000) { /* |x|==1 */
|
if(ix==0x3f800000) { /* |x|==1 */
|
if(hx>0) return 0.0; /* acos(1) = 0 */
|
if(hx>0) return 0.0; /* acos(1) = 0 */
|
else return pi+(float)2.0*pio2_lo; /* acos(-1)= pi */
|
else return pi+(float)2.0*pio2_lo; /* acos(-1)= pi */
|
} else if(ix>0x3f800000) { /* |x| >= 1 */
|
} else if(ix>0x3f800000) { /* |x| >= 1 */
|
return (x-x)/(x-x); /* acos(|x|>1) is NaN */
|
return (x-x)/(x-x); /* acos(|x|>1) is NaN */
|
}
|
}
|
if(ix<0x3f000000) { /* |x| < 0.5 */
|
if(ix<0x3f000000) { /* |x| < 0.5 */
|
if(ix<=0x23000000) return pio2_hi+pio2_lo;/*if|x|<2**-57*/
|
if(ix<=0x23000000) return pio2_hi+pio2_lo;/*if|x|<2**-57*/
|
z = x*x;
|
z = x*x;
|
p = z*(pS0+z*(pS1+z*(pS2+z*(pS3+z*(pS4+z*pS5)))));
|
p = z*(pS0+z*(pS1+z*(pS2+z*(pS3+z*(pS4+z*pS5)))));
|
q = one+z*(qS1+z*(qS2+z*(qS3+z*qS4)));
|
q = one+z*(qS1+z*(qS2+z*(qS3+z*qS4)));
|
r = p/q;
|
r = p/q;
|
return pio2_hi - (x - (pio2_lo-x*r));
|
return pio2_hi - (x - (pio2_lo-x*r));
|
} else if (hx<0) { /* x < -0.5 */
|
} else if (hx<0) { /* x < -0.5 */
|
z = (one+x)*(float)0.5;
|
z = (one+x)*(float)0.5;
|
p = z*(pS0+z*(pS1+z*(pS2+z*(pS3+z*(pS4+z*pS5)))));
|
p = z*(pS0+z*(pS1+z*(pS2+z*(pS3+z*(pS4+z*pS5)))));
|
q = one+z*(qS1+z*(qS2+z*(qS3+z*qS4)));
|
q = one+z*(qS1+z*(qS2+z*(qS3+z*qS4)));
|
s = __ieee754_sqrtf(z);
|
s = __ieee754_sqrtf(z);
|
r = p/q;
|
r = p/q;
|
w = r*s-pio2_lo;
|
w = r*s-pio2_lo;
|
return pi - (float)2.0*(s+w);
|
return pi - (float)2.0*(s+w);
|
} else { /* x > 0.5 */
|
} else { /* x > 0.5 */
|
__int32_t idf;
|
__int32_t idf;
|
z = (one-x)*(float)0.5;
|
z = (one-x)*(float)0.5;
|
s = __ieee754_sqrtf(z);
|
s = __ieee754_sqrtf(z);
|
df = s;
|
df = s;
|
GET_FLOAT_WORD(idf,df);
|
GET_FLOAT_WORD(idf,df);
|
SET_FLOAT_WORD(df,idf&0xfffff000);
|
SET_FLOAT_WORD(df,idf&0xfffff000);
|
c = (z-df*df)/(s+df);
|
c = (z-df*df)/(s+df);
|
p = z*(pS0+z*(pS1+z*(pS2+z*(pS3+z*(pS4+z*pS5)))));
|
p = z*(pS0+z*(pS1+z*(pS2+z*(pS3+z*(pS4+z*pS5)))));
|
q = one+z*(qS1+z*(qS2+z*(qS3+z*qS4)));
|
q = one+z*(qS1+z*(qS2+z*(qS3+z*qS4)));
|
r = p/q;
|
r = p/q;
|
w = r*s+c;
|
w = r*s+c;
|
return (float)2.0*(df+w);
|
return (float)2.0*(df+w);
|
}
|
}
|
}
|
}
|
|
|
