summaryrefslogtreecommitdiff
path: root/src/math/atan2f.c
diff options
context:
space:
mode:
Diffstat (limited to 'src/math/atan2f.c')
-rw-r--r--src/math/atan2f.c59
1 files changed, 25 insertions, 34 deletions
diff --git a/src/math/atan2f.c b/src/math/atan2f.c
index 96839cba..c634d00f 100644
--- a/src/math/atan2f.c
+++ b/src/math/atan2f.c
@@ -15,72 +15,63 @@
#include "libm.h"
-static const volatile float
-tiny = 1.0e-30;
static const float
-pi_o_4 = 7.8539818525e-01, /* 0x3f490fdb */
-pi_o_2 = 1.5707963705e+00, /* 0x3fc90fdb */
-pi = 3.1415927410e+00; /* 0x40490fdb */
-static const volatile float
+pi = 3.1415927410e+00, /* 0x40490fdb */
pi_lo = -8.7422776573e-08; /* 0xb3bbbd2e */
float atan2f(float y, float x)
{
float z;
- int32_t k,m,hx,hy,ix,iy;
+ uint32_t m,ix,iy;
- GET_FLOAT_WORD(hx, x);
- ix = hx & 0x7fffffff;
- GET_FLOAT_WORD(hy, y);
- iy = hy & 0x7fffffff;
- if (ix > 0x7f800000 || iy > 0x7f800000) /* x or y is NaN */
+ if (isnan(x) || isnan(y))
return x+y;
- if (hx == 0x3f800000) /* x=1.0 */
+ GET_FLOAT_WORD(ix, x);
+ GET_FLOAT_WORD(iy, y);
+ if (ix == 0x3f800000) /* x=1.0 */
return atanf(y);
- m = ((hy>>31)&1) | ((hx>>30)&2); /* 2*sign(x)+sign(y) */
+ m = ((iy>>31)&1) | ((ix>>30)&2); /* 2*sign(x)+sign(y) */
+ ix &= 0x7fffffff;
+ iy &= 0x7fffffff;
/* when y = 0 */
if (iy == 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 */
+ case 1: return y; /* atan(+-0,+anything)=+-0 */
+ case 2: return pi; /* atan(+0,-anything) = pi */
+ case 3: return -pi; /* atan(-0,-anything) =-pi */
}
}
/* when x = 0 */
if (ix == 0)
- return hy < 0 ? -pi_o_2-tiny : pi_o_2+tiny;
+ return m&1 ? -pi/2 : pi/2;
/* when x is INF */
if (ix == 0x7f800000) {
if (iy == 0x7f800000) {
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 3.0f*pi_o_4+tiny; /*atan(+INF,-INF)*/
- case 3: return -3.0f*pi_o_4-tiny; /*atan(-INF,-INF)*/
+ case 0: return pi/4; /* atan(+INF,+INF) */
+ case 1: return -pi/4; /* atan(-INF,+INF) */
+ case 2: return 3*pi/4; /*atan(+INF,-INF)*/
+ case 3: return -3*pi/4; /*atan(-INF,-INF)*/
}
} else {
switch (m) {
case 0: return 0.0f; /* atan(+...,+INF) */
case 1: return -0.0f; /* atan(-...,+INF) */
- case 2: return pi+tiny; /* atan(+...,-INF) */
- case 3: return -pi-tiny; /* atan(-...,-INF) */
+ case 2: return pi; /* atan(+...,-INF) */
+ case 3: return -pi; /* atan(-...,-INF) */
}
}
}
- /* when y is INF */
- if (iy == 0x7f800000)
- return hy < 0 ? -pi_o_2-tiny : pi_o_2+tiny;
+ /* |y/x| > 0x1p26 */
+ if (ix+(26<<23) < iy || iy == 0x7f800000)
+ return m&1 ? -pi/2 : pi/2;
- /* compute y/x */
- k = (iy-ix)>>23;
- if (k > 26) { /* |y/x| > 2**26 */
- z = pi_o_2 + 0.5f*pi_lo;
- m &= 1;
- } else if (k < -26 && hx < 0) /* 0 > |y|/x > -2**-26 */
+ /* z = atan(|y/x|) with correct underflow */
+ if ((m&2) && iy+(26<<23) < ix) /*|y/x| < 0x1p-26, x < 0 */
z = 0.0;
- else /* safe to do y/x */
+ else
z = atanf(fabsf(y/x));
switch (m) {
case 0: return z; /* atan(+,+) */