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  • Committer: Package Import Robot
  • Author(s): Matthias Klose
  • Date: 2011-10-04 17:48:26 UTC
  • mfrom: (216.1.23 oneiric)
  • Revision ID: package-import@ubuntu.com-20111004174826-2cyb9ewn3ucymlsx
Tags: 2.13-20ubuntu5
https://launchpad.net/bugs/853688
libc6-dev: Don't break the current {gnat,gcj}-4.4-base versons. LP: #853688.

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sysdeps/ieee754/ldbl-128ibm/e_atan2l.c
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 * Method :
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 *      1. Reduce y to positive by atan2l(y,x)=-atan2l(-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-300L,
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zero  = 0.0,
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pi_o_4  = 7.85398163397448309615660845819875699e-01L, /* 3ffe921fb54442d18469898cc51701b8 */
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pi      = 3.14159265358979323846264338327950280e+00L, /* 4000921fb54442d18469898cc51701b8 */
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pi_lo   = 8.67181013012378102479704402604335225e-35L; /* 3f8dcd129024e088a67cc74020bbea64 */
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long double
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__ieee754_atan2l(long double y, long double x)
 
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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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{
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        long double z;
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        int64_t k,m,hx,hy,ix,iy;
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        if((iy|(ly&0x7fffffffffffffffLL))==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 = (iy-ix)>>52;
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        if(k > 120) z=pi_o_2+0.5L*pi_lo;        /* |y/x| >  2**120 */
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        else if(hx<0&&k<-120) z=0.0L;           /* |y|/x < -2**120 */
 
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        if(k > 120) z=pi_o_2+0.5L*pi_lo;        /* |y/x| >  2**120 */
 
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        else if(hx<0&&k<-120) z=0.0L;           /* |y|/x < -2**120 */
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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: 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)