npy_bool
ufunc_signbit(npy_double a)
{
return npy_signbit(a) != 0;
}
double npy_atan2(double y, double x)
{
npy_int32 k, m, iy, ix, hx, hy;
npy_uint32 lx,ly;
double z;
EXTRACT_WORDS(hx, lx, x);
ix = hx & 0x7fffffff;
EXTRACT_WORDS(hy, ly, y);
iy = hy & 0x7fffffff;
/* if x or y is nan, return nan */
if (npy_isnan(x * y)) {
return x + y;
}
if (x == 1.0) {
return npy_atan(y);
}
m = 2 * npy_signbit(x) + npy_signbit(y);
if (y == 0.0) {
switch(m) {
case 0:
case 1: return y; /* atan(+-0,+anything)=+-0 */
case 2: return NPY_PI;/* atan(+0,-anything) = pi */
case 3: return -NPY_PI;/* atan(-0,-anything) =-pi */
}
}
if (x == 0.0) {
return y > 0 ? NPY_PI_2 : -NPY_PI_2;
}
if (npy_isinf(x)) {
if (npy_isinf(y)) {
switch(m) {
case 0: return NPY_PI_4;/* atan(+INF,+INF) */
case 1: return -NPY_PI_4;/* atan(-INF,+INF) */
case 2: return 3.0*NPY_PI_4;/*atan(+INF,-INF)*/
case 3: return -3.0*NPY_PI_4;/*atan(-INF,-INF)*/
}
} else {
switch(m) {
case 0: return NPY_PZERO; /* atan(+...,+INF) */
case 1: return NPY_NZERO; /* atan(-...,+INF) */
case 2: return NPY_PI; /* atan(+...,-INF) */
case 3: return -NPY_PI; /* atan(-...,-INF) */
}
}
}
if (npy_isinf(y)) {
return y > 0 ? NPY_PI_2 : -NPY_PI_2;
}
/* compute y/x */
k = (iy - ix) >> 20;
if (k > 60) { /* |y/x| > 2**60 */
z = NPY_PI_2 + 0.5 * NPY_DBL_EPSILON;
m &= 1;
} else if (hx < 0 && k < -60) {
z = 0.0; /* 0 > |y|/x > -2**-60 */
} else {
z = npy_atan(npy_fabs(y/x)); /* safe to do y/x */
}
switch (m) {
case 0: return z ; /* atan(+,+) */
case 1: return -z ; /* atan(-,+) */
case 2: return NPY_PI - (z - NPY_DBL_EPSILON);/* atan(+,-) */
default: /* case 3 */
return (z - NPY_DBL_EPSILON) - NPY_PI;/* atan(-,-) */
}
}
npy_bool
ufunc_signbitf(npy_float a)
{
return npy_signbit(a) != 0;
}
