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Diffstat (limited to 'libquadmath/math/atan2q.c')
| -rw-r--r-- | libquadmath/math/atan2q.c | 120 |
1 files changed, 120 insertions, 0 deletions
diff --git a/libquadmath/math/atan2q.c b/libquadmath/math/atan2q.c new file mode 100644 index 000000000..fbe64d62b --- /dev/null +++ b/libquadmath/math/atan2q.c @@ -0,0 +1,120 @@ +/* e_atan2l.c -- long double version of e_atan2.c. + * Conversion to long double by Jakub Jelinek, jj@ultra.linux.cz. + */ + +/* + * ==================================================== + * 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. + * ==================================================== + */ + +/* atan2q(y,x) + * Method : + * 1. Reduce y to positive by atan2q(y,x)=-atan2q(-y,x). + * 2. Reduce x to positive by (if x and y are unexceptional): + * ARG (x+iy) = arctan(y/x) ... if x > 0, + * ARG (x+iy) = pi - arctan[y/(-x)] ... if x < 0, + * + * Special cases: + * + * ATAN2((anything), NaN ) is NaN; + * ATAN2(NAN , (anything) ) is NaN; + * ATAN2(+-0, +(anything but NaN)) is +-0 ; + * ATAN2(+-0, -(anything but NaN)) is +-pi ; + * ATAN2(+-(anything but 0 and NaN), 0) is +-pi/2; + * ATAN2(+-(anything but INF and NaN), +INF) is +-0 ; + * ATAN2(+-(anything but INF and NaN), -INF) is +-pi; + * ATAN2(+-INF,+INF ) is +-pi/4 ; + * ATAN2(+-INF,-INF ) is +-3pi/4; + * ATAN2(+-INF, (anything but,0,NaN, and INF)) is +-pi/2; + * + * Constants: + * The hexadecimal values are the intended ones for the following + * constants. The decimal values may be used, provided that the + * compiler will convert from decimal to binary accurately enough + * to produce the hexadecimal values shown. + */ + +#include "quadmath-imp.h" + +static const __float128 +tiny = 1.0e-4900Q, +zero = 0.0, +pi_o_4 = 7.85398163397448309615660845819875699e-01Q, /* 3ffe921fb54442d18469898cc51701b8 */ +pi_o_2 = 1.57079632679489661923132169163975140e+00Q, /* 3fff921fb54442d18469898cc51701b8 */ +pi = 3.14159265358979323846264338327950280e+00Q, /* 4000921fb54442d18469898cc51701b8 */ +pi_lo = 8.67181013012378102479704402604335225e-35Q; /* 3f8dcd129024e088a67cc74020bbea64 */ + +__float128 +atan2q (__float128 y, __float128 x) +{ + __float128 z; + int64_t k,m,hx,hy,ix,iy; + uint64_t lx,ly; + + GET_FLT128_WORDS64(hx,lx,x); + ix = hx&0x7fffffffffffffffLL; + GET_FLT128_WORDS64(hy,ly,y); + iy = hy&0x7fffffffffffffffLL; + if(((ix|((lx|-lx)>>63))>0x7fff000000000000LL)|| + ((iy|((ly|-ly)>>63))>0x7fff000000000000LL)) /* x or y is NaN */ + return x+y; + if(((hx-0x3fff000000000000LL)|lx)==0) return atanq(y); /* x=1.0Q */ + m = ((hy>>63)&1)|((hx>>62)&2); /* 2*sign(x)+sign(y) */ + + /* when y = 0 */ + if((iy|ly)==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|lx)==0) return (hy<0)? -pi_o_2-tiny: pi_o_2+tiny; + + /* when x is INF */ + if(ix==0x7fff000000000000LL) { + if(iy==0x7fff000000000000LL) { + 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 3.0Q*pi_o_4+tiny;/*atan(+INF,-INF)*/ + case 3: return -3.0Q*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==0x7fff000000000000LL) return (hy<0)? -pi_o_2-tiny: pi_o_2+tiny; + + /* compute y/x */ + k = (iy-ix)>>48; + if(k > 120) z=pi_o_2+0.5Q*pi_lo; /* |y/x| > 2**120 */ + else if(hx<0&&k<-120) z=0.0Q; /* |y|/x < -2**120 */ + else z=atanq(fabsq(y/x)); /* safe to do y/x */ + switch (m) { + case 0: return z ; /* atan(+,+) */ + case 1: { + uint64_t zh; + GET_FLT128_MSW64(zh,z); + SET_FLT128_MSW64(z,zh ^ 0x8000000000000000ULL); + } + return z ; /* atan(-,+) */ + case 2: return pi-(z-pi_lo);/* atan(+,-) */ + default: /* case 3 */ + return (z-pi_lo)-pi;/* atan(-,-) */ + } +} |