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  • Committer: Package Import Robot
  • Author(s): Matthias Klose
  • Date: 2012-02-08 01:58:09 UTC
  • mfrom: (1.5.3) (288.1.12 precise)
  • Revision ID: package-import@ubuntu.com-20120208015809-ulscst7uteq3e22z
Tags: 2.15~pre6-0ubuntu10
Merge from Debian (r5151, 2.13-26).

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sysdeps/ieee754/ldbl-96/e_atan2l.c
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 * ====================================================
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 */
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#if defined(LIBM_SCCS) && !defined(lint)
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static char rcsid[] = "$NetBSD: $";
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#endif
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/* __ieee754_atan2l(y,x)
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 * Method :
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 *      1. Reduce y to positive by atan2(y,x)=-atan2(-y,x).
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 *      2. Reduce x to positive by (if x and y are unexceptional):
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 *              ARG (x+iy) = arctan(y/x)           ... if x > 0,
 
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 *              ARG (x+iy) = arctan(y/x)           ... if x > 0,
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 *              ARG (x+iy) = pi - arctan[y/(-x)]   ... if x < 0,
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 *
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 * Special cases:
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#include "math.h"
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#include "math_private.h"
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#ifdef __STDC__
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static const long double
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#else
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static long double
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#endif
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tiny  = 1.0e-4900L,
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zero  = 0.0,
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pi_o_4  = 7.85398163397448309628202E-01L, /* 0x3FFE, 0xC90FDAA2, 0x2168C235 */
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pi      = 3.14159265358979323851281E+00L, /* 0x4000, 0xC90FDAA2, 0x2168C235 */
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pi_lo   = -5.01655761266833202345176e-20L;/* 0xBFBE, 0xECE675D1, 0xFC8F8CBB */
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#ifdef __STDC__
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        long double __ieee754_atan2l(long double y, long double x)
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#else
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        long double __ieee754_atan2l(y,x)
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        long double  y,x;
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#endif
 
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long double
 
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__ieee754_atan2l (long double y, long double x)
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{
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        long double z;
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        int32_t k,m,hx,hy,ix,iy;
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        if((iy|ly)==0) {
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            switch(m) {
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                case 0:
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                case 1: return y;       /* atan(+-0,+anything)=+-0 */
 
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                case 1: return y;       /* atan(+-0,+anything)=+-0 */
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                case 2: return  pi+tiny;/* atan(+0,-anything) = pi */
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                case 3: return -pi-tiny;/* atan(-0,-anything) =-pi */
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            }
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    /* compute y/x */
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        k = sy-sx;
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        if(k > 70) z=pi_o_2+0.5*pi_lo;  /* |y/x| >  2**70 */
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        else if(sx>=0x8000&&k<-70) z=0.0;       /* |y|/x < -2**70 */
 
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        if(k > 70) z=pi_o_2+0.5*pi_lo;  /* |y/x| >  2**70 */
 
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        else if(sx>=0x8000&&k<-70) z=0.0;       /* |y|/x < -2**70 */
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        else z=__atanl(fabsl(y/x));     /* safe to do y/x */
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        switch (m) {
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            case 0: return       z  ;   /* atan(+,+) */
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            case 1: {
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                      u_int32_t sz;
 
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                      u_int32_t sz;
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                      GET_LDOUBLE_EXP(sz,z);
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                      SET_LDOUBLE_EXP(z,sz ^ 0x8000);
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                    }
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                    return       z  ;   /* atan(-,+) */
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            case 2: return  pi-(z-pi_lo);/* atan(+,-) */
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            default: /* case 3 */
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                    return  (z-pi_lo)-pi;/* atan(-,-) */
 
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                    return  (z-pi_lo)-pi;/* atan(-,-) */
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        }
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}
 
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strong_alias (__ieee754_atan2l, __atan2l_finite)