doubledouble atan2(const doubledouble& qy, const doubledouble& qx) { // Based on GNU libc atan2.c
static const double one=1.0, zero=0.0; double x, y;
x=qx.h(); y=qy.h();
double signx, signy;
if (x!=x) return qx; // x=NaN
if (y!=y) return qy;
#ifndef WIN32
signy=copysign(one,y);
signx=copysign(one,x);
#else
signy=_copysign(one,y);
signx=_copysign(one,x);
#endif
if (y==zero) return signx==one ? qy : Qcopysign(doubledouble::Pi,signy);
if (x==zero) return Qcopysign(doubledouble::Pion2,signy);
// Dustin Graves 2002Apr06 #ifndef WIN32
if (DD_ISINF(x)) {
if (DD_ISINF(y)) return Qcopysign(signx==one ? doubledouble::Pion4 : 3.0*doubledouble::Pion4,signy);
else return Qcopysign(signx==one ? doubledouble(0.0) : doubledouble::Pi,signy);
}
if (DD_ISINF(y)) return Qcopysign(doubledouble::Pion2,signy);
//#else
// if (_isnan(x)) {
// if (_isnan(y)) return Qcopysign(signx==one ? doubledouble::Pion4 : 3.0*doubledouble::Pion4,signy);
// else return Qcopysign(signx==one ? doubledouble(0.0) : doubledouble::Pi,signy);
// }
// if (_isnan(y)) return Qcopysign(doubledouble::Pion2,signy);
//#endif
doubledouble aqy=fabs(qy);
if (x<0.0) // X is negative.
return Qcopysign(doubledouble::Pi-atan(aqy/(-qx)),signy);
return Qcopysign(atan(aqy/qx),signy);
}
int
get_double_expn(double x)
{
int i = 0;
double y;
if (x == 0.0) {
return INT_MIN;
}
if (DD_ISINF(x) || DD_ISNAN(x)) {
return INT_MAX;
}
y = fabs(x);
if (y < 1.0) {
while (y < 1.0) {
y *= 2.0;
i++;
}
return -i;
} else if (y >= 2.0) {
while (y >= 2.0) {
y *= 0.5;
i++;
}
return i;
}
return 0;
}
