0,0 → 1,93 |
/* Copyright (C) 1994 DJ Delorie, see COPYING.DJ for details */ |
/* e_asinf.c -- float version of e_asin.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_asinf.c,v 1.2 1994/08/18 23:05:05 jtc Exp $"; |
#endif |
|
#include "math.h" |
#include "math_private.h" |
|
#ifdef __STDC__ |
static const float |
#else |
static float |
#endif |
one = 1.0000000000e+00, /* 0x3F800000 */ |
huge = 1.000e+30, |
pio2_hi = 1.5707962513e+00, /* 0x3fc90fda */ |
pio2_lo = 7.5497894159e-08, /* 0x33a22168 */ |
pio4_hi = 7.8539818525e-01, /* 0x3f490fdb */ |
/* coefficient for R(x^2) */ |
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_asinf(float x) |
#else |
float __ieee754_asinf(x) |
float x; |
#endif |
{ |
float t,w,p,q,c,r,s; |
int32_t hx,ix; |
GET_FLOAT_WORD(hx,x); |
ix = hx&0x7fffffff; |
if(ix==0x3f800000) { |
/* asin(1)=+-pi/2 with inexact */ |
return x*pio2_hi+x*pio2_lo; |
} else if(ix> 0x3f800000) { /* |x|>= 1 */ |
return (x-x)/(x-x); /* asin(|x|>1) is NaN */ |
} else if (ix<0x3f000000) { /* |x|<0.5 */ |
if(ix<0x32000000) { /* if |x| < 2**-27 */ |
if(huge+x>one) return x;/* return x with inexact if x!=0*/ |
} else |
t = x*x; |
p = t*(pS0+t*(pS1+t*(pS2+t*(pS3+t*(pS4+t*pS5))))); |
q = one+t*(qS1+t*(qS2+t*(qS3+t*qS4))); |
w = p/q; |
return x+x*w; |
} |
/* 1> |x|>= 0.5 */ |
w = one-fabsf(x); |
t = w*(float)0.5; |
p = t*(pS0+t*(pS1+t*(pS2+t*(pS3+t*(pS4+t*pS5))))); |
q = one+t*(qS1+t*(qS2+t*(qS3+t*qS4))); |
s = sqrtf(t); |
if(ix>=0x3F79999A) { /* if |x| > 0.975 */ |
w = p/q; |
t = pio2_hi-((float)2.0*(s+s*w)-pio2_lo); |
} else { |
int32_t iw; |
w = s; |
GET_FLOAT_WORD(iw,w); |
SET_FLOAT_WORD(w,iw&0xfffff000); |
c = (t-w*w)/(s+w); |
r = p/q; |
p = (float)2.0*s*r-(pio2_lo-(float)2.0*c); |
q = pio4_hi-(float)2.0*w; |
t = pio4_hi-(p-q); |
} |
if(hx>0) return t; else return -t; |
} |