| /* 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. |
| * ==================================================== |
| */ |
| |
| #include <sys/cdefs.h> |
| __FBSDID("$FreeBSD$"); |
| |
| #include "math.h" |
| #include "math_private.h" |
| |
| static const float |
| one = 1.0000000000e+00, /* 0x3F800000 */ |
| pi = 3.1415925026e+00, /* 0x40490fda */ |
| pio2_hi = 1.5707962513e+00; /* 0x3fc90fda */ |
| static volatile float |
| pio2_lo = 7.5497894159e-08; /* 0x33a22168 */ |
| static const float |
| pS0 = 1.6666586697e-01, |
| pS1 = -4.2743422091e-02, |
| pS2 = -8.6563630030e-03, |
| qS1 = -7.0662963390e-01; |
| |
| float |
| __ieee754_acosf(float x) |
| { |
| 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(ix==0x3f800000) { /* |x| == 1 */ |
| if(hx>0) return 0.0; /* acos(1) = 0 */ |
| else return pi+(float)2.0*pio2_lo; /* acos(-1)= pi */ |
| } |
| return (x-x)/(x-x); /* acos(|x|>1) is NaN */ |
| } |
| if(ix<0x3f000000) { /* |x| < 0.5 */ |
| if(ix<=0x32800000) return pio2_hi+pio2_lo;/*if|x|<2**-26*/ |
| z = x*x; |
| p = z*(pS0+z*(pS1+z*pS2)); |
| q = one+z*qS1; |
| 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)); |
| q = one+z*qS1; |
| 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)); |
| q = one+z*qS1; |
| r = p/q; |
| w = r*s+c; |
| return (float)2.0*(df+w); |
| } |
| } |
