/* e_atan2f.c -- float version of e_atan2.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. * ==================================================== */ #ifndef lint static char rcsid[] = "$Id: e_atan2f.c,v 1.1.1.1 1994/08/19 09:39:54 jkh Exp $"; #endif #include "math.h" #include "math_private.h" #ifdef __STDC__ static const float #else static float #endif tiny = 1.0e-30, zero = 0.0, pi_o_4 = 7.8539818525e-01, /* 0x3f490fdb */ pi_o_2 = 1.5707963705e+00, /* 0x3fc90fdb */ pi = 3.1415925026e+00, /* 0x40490fda */ pi_lo = 1.5099578832e-07; /* 0x34222168 */ #ifdef __STDC__ float __ieee754_atan2f(float y, float x) #else float __ieee754_atan2f(y,x) float y,x; #endif { float z; int32_t k,m,hx,hy,ix,iy; GET_FLOAT_WORD(hx,x); ix = hx&0x7fffffff; GET_FLOAT_WORD(hy,y); iy = hy&0x7fffffff; if((ix>0x7f800000)|| (iy>0x7f800000)) /* x or y is NaN */ return x+y; if(hx==0x3f800000) return atanf(y); /* x=1.0 */ m = ((hy>>31)&1)|((hx>>30)&2); /* 2*sign(x)+sign(y) */ /* when y = 0 */ if(iy==0) { switch(m) { case 0: case 1: return y; /* atan(+-0,+anything)=+-0 */ case 2: return pi+tiny;/* atan(+0,-anything) = pi */ case 3: return -pi-tiny;/* atan(-0,-anything) =-pi */ } } /* when x = 0 */ if(ix==0) return (hy<0)? -pi_o_2-tiny: pi_o_2+tiny; /* when x is INF */ if(ix==0x7f800000) { if(iy==0x7f800000) { switch(m) { case 0: return pi_o_4+tiny;/* atan(+INF,+INF) */ case 1: return -pi_o_4-tiny;/* atan(-INF,+INF) */ case 2: return (float)3.0*pi_o_4+tiny;/*atan(+INF,-INF)*/ case 3: return (float)-3.0*pi_o_4-tiny;/*atan(-INF,-INF)*/ } } else { switch(m) { case 0: return zero ; /* atan(+...,+INF) */ case 1: return -zero ; /* atan(-...,+INF) */ case 2: return pi+tiny ; /* atan(+...,-INF) */ case 3: return -pi-tiny ; /* atan(-...,-INF) */ } } } /* when y is INF */ if(iy==0x7f800000) return (hy<0)? -pi_o_2-tiny: pi_o_2+tiny; /* compute y/x */ k = (iy-ix)>>23; if(k > 60) z=pi_o_2+(float)0.5*pi_lo; /* |y/x| > 2**60 */ else if(hx<0&&k<-60) z=0.0; /* |y|/x < -2**60 */ else z=atanf(fabsf(y/x)); /* safe to do y/x */ switch (m) { case 0: return z ; /* atan(+,+) */ case 1: { u_int32_t zh; GET_FLOAT_WORD(zh,z); SET_FLOAT_WORD(z,zh ^ 0x80000000); } return z ; /* atan(-,+) */ case 2: return pi-(z-pi_lo);/* atan(+,-) */ default: /* case 3 */ return (z-pi_lo)-pi;/* atan(-,-) */ } }