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lightning-sunbird  0.9+nobinonly
Functions | Variables
e_atan2.c File Reference
#include "fdlibm.h"

Go to the source code of this file.

Functions

double __ieee754_atan2 (double y, double x)

Variables

static double tiny = 1.0e-300
static double zero = 0.0
static double pi_o_4 = 7.8539816339744827900E-01
static double pi_o_2 = 1.5707963267948965580E+00
static double pi = 3.1415926535897931160E+00
static double pi_lo = 1.2246467991473531772E-16

Function Documentation

double __ieee754_atan2 ( double  y,
double  x 
)

Definition at line 97 of file e_atan2.c.

{  
        fd_twoints ux, uy, uz;
       double z;
       int k,m,hx,hy,ix,iy;
       unsigned lx,ly;

        ux.d = x; uy.d = y;
       hx = __HI(ux); ix = hx&0x7fffffff;
       lx = __LO(ux);
       hy = __HI(uy); iy = hy&0x7fffffff;
       ly = __LO(uy);
       if(((ix|((lx|-(int)lx)>>31))>0x7ff00000)||
          ((iy|((ly|-(int)ly)>>31))>0x7ff00000)) /* x or y is NaN */
          return x+y;
       if(((hx-0x3ff00000)|lx)==0) return fd_atan(y);   /* x=1.0 */
       m = ((hy>>31)&1)|((hx>>30)&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==0x7ff00000) {
           if(iy==0x7ff00000) {
              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  3.0*pi_o_4+tiny;/*atan(+INF,-INF)*/
                  case 3: return -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==0x7ff00000) return (hy<0)? -pi_o_2-tiny: pi_o_2+tiny;

    /* compute y/x */
       k = (iy-ix)>>20;
       if(k > 60) z=pi_o_2+0.5*pi_lo;     /* |y/x| >  2**60 */
       else if(hx<0&&k<-60) z=0.0;        /* |y|/x < -2**60 */
       else z=fd_atan(fd_fabs(y/x));             /* safe to do y/x */
       switch (m) {
           case 0: return       z  ;      /* atan(+,+) */
           case 1: uz.d = z;
                    __HI(uz) ^= 0x80000000;
                    z = uz.d;
                  return       z  ;       /* atan(-,+) */
           case 2: return  pi-(z-pi_lo);/* atan(+,-) */
           default: /* case 3 */
                  return  (z-pi_lo)-pi;/* atan(-,-) */
       }
}

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Variable Documentation

double pi = 3.1415926535897931160E+00 [static]

Definition at line 91 of file e_atan2.c.

double pi_lo = 1.2246467991473531772E-16 [static]

Definition at line 92 of file e_atan2.c.

double pi_o_2 = 1.5707963267948965580E+00 [static]

Definition at line 90 of file e_atan2.c.

double pi_o_4 = 7.8539816339744827900E-01 [static]

Definition at line 89 of file e_atan2.c.

double tiny = 1.0e-300 [static]

Definition at line 87 of file e_atan2.c.

double zero = 0.0 [static]

Definition at line 88 of file e_atan2.c.