SDL  2.0
e_atan2.c File Reference
#include "math_libm.h"
#include "math_private.h"
+ Include dependency graph for e_atan2.c:

Go to the source code of this file.

Functions

double attribute_hidden __ieee754_atan2 (double y, double x)
 

Variables

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

Function Documentation

double attribute_hidden __ieee754_atan2 ( double  y,
double  x 
)

Definition at line 50 of file e_atan2.c.

References atan(), EXTRACT_WORDS, fabs, GET_HIGH_WORD, pi, pi_lo, pi_o_2, pi_o_4, SET_HIGH_WORD, tiny, and zero.

51 {
52  double z;
53  int32_t k,m,hx,hy,ix,iy;
54  u_int32_t lx,ly;
55 
56  EXTRACT_WORDS(hx,lx,x);
57  ix = hx&0x7fffffff;
58  EXTRACT_WORDS(hy,ly,y);
59  iy = hy&0x7fffffff;
60  if(((ix|((lx|-(int32_t)lx)>>31))>0x7ff00000)||
61  ((iy|((ly|-(int32_t)ly)>>31))>0x7ff00000)) /* x or y is NaN */
62  return x+y;
63  if(((hx-0x3ff00000)|lx)==0) return atan(y); /* x=1.0 */
64  m = ((hy>>31)&1)|((hx>>30)&2); /* 2*sign(x)+sign(y) */
65 
66  /* when y = 0 */
67  if((iy|ly)==0) {
68  switch(m) {
69  case 0:
70  case 1: return y; /* atan(+-0,+anything)=+-0 */
71  case 2: return pi+tiny;/* atan(+0,-anything) = pi */
72  case 3: return -pi-tiny;/* atan(-0,-anything) =-pi */
73  }
74  }
75  /* when x = 0 */
76  if((ix|lx)==0) return (hy<0)? -pi_o_2-tiny: pi_o_2+tiny;
77 
78  /* when x is INF */
79  if(ix==0x7ff00000) {
80  if(iy==0x7ff00000) {
81  switch(m) {
82  case 0: return pi_o_4+tiny;/* atan(+INF,+INF) */
83  case 1: return -pi_o_4-tiny;/* atan(-INF,+INF) */
84  case 2: return 3.0*pi_o_4+tiny;/* atan(+INF,-INF) */
85  case 3: return -3.0*pi_o_4-tiny;/* atan(-INF,-INF) */
86  }
87  } else {
88  switch(m) {
89  case 0: return zero ; /* atan(+...,+INF) */
90  case 1: return -zero ; /* atan(-...,+INF) */
91  case 2: return pi+tiny ; /* atan(+...,-INF) */
92  case 3: return -pi-tiny ; /* atan(-...,-INF) */
93  }
94  }
95  }
96  /* when y is INF */
97  if(iy==0x7ff00000) return (hy<0)? -pi_o_2-tiny: pi_o_2+tiny;
98 
99  /* compute y/x */
100  k = (iy-ix)>>20;
101  if(k > 60) z=pi_o_2+0.5*pi_lo; /* |y/x| > 2**60 */
102  else if(hx<0&&k<-60) z=0.0; /* |y|/x < -2**60 */
103  else z=atan(fabs(y/x)); /* safe to do y/x */
104  switch (m) {
105  case 0: return z ; /* atan(+,+) */
106  case 1: {
107  u_int32_t zh;
108  GET_HIGH_WORD(zh,z);
109  SET_HIGH_WORD(z,zh ^ 0x80000000);
110  }
111  return z ; /* atan(-,+) */
112  case 2: return pi-(z-pi_lo);/* atan(+,-) */
113  default: /* case 3 */
114  return (z-pi_lo)-pi;/* atan(-,-) */
115  }
116 }
#define GET_HIGH_WORD(i, d)
Definition: math_private.h:103
static const double pi
Definition: e_atan2.c:47
static const double tiny
Definition: e_atan2.c:43
signed int int32_t
GLint GLint GLint GLint GLint x
Definition: SDL_opengl.h:1567
const GLfloat * m
static const double pi_o_4
Definition: e_atan2.c:45
#define SET_HIGH_WORD(d, v)
Definition: math_private.h:131
static const double pi_lo
Definition: e_atan2.c:48
static const double zero
Definition: e_atan2.c:44
unsigned int u_int32_t
Definition: math_private.h:29
GLint GLint GLint GLint GLint GLint y
Definition: SDL_opengl.h:1567
#define EXTRACT_WORDS(ix0, ix1, d)
Definition: math_private.h:93
static const double pi_o_2
Definition: e_atan2.c:46
#define fabs
Definition: math_private.h:36
GLdouble GLdouble z
double atan(double x)
Definition: s_atan.c:67

Variable Documentation

const double pi = 3.1415926535897931160E+00
static

Definition at line 47 of file e_atan2.c.

Referenced by __ieee754_atan2().

const double pi_lo = 1.2246467991473531772E-16
static

Definition at line 48 of file e_atan2.c.

Referenced by __ieee754_atan2().

const double pi_o_2 = 1.5707963267948965580E+00
static

Definition at line 46 of file e_atan2.c.

Referenced by __ieee754_atan2().

const double pi_o_4 = 7.8539816339744827900E-01
static

Definition at line 45 of file e_atan2.c.

Referenced by __ieee754_atan2().

const double tiny = 1.0e-300
static

Definition at line 43 of file e_atan2.c.

Referenced by __ieee754_atan2().

const double zero = 0.0
static

Definition at line 44 of file e_atan2.c.

Referenced by __ieee754_atan2().