hx = __HI(x); ix = hx&0x7fffffff; lx = __LO(x); hy = __HI(y); iy = hy&0x7fffffff; ly = __LO(y);
ux.d = x; uy.d = y; hx = __HI(ux); ix = hx&0x7fffffff; lx = __LO(ux); hy = __HI(uy); iy = hy&0x7fffffff; ly = __LO(uy);
	double __ieee754_atan2(double y, double x)#else	double __ieee754_atan2(y,x)	double  y,x;#endif{  	double z;	int k,m,hx,hy,ix,iy;	unsigned lx,ly;	hx = __HI(x); ix = hx&0x7fffffff;	lx = __LO(x);	hy = __HI(y); iy = hy&0x7fffffff;	ly = __LO(y);	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: __HI(z) ^= 0x80000000;		    return       z  ;	/* atan(-,+) */	    case 2: return  pi-(z-pi_lo);/* atan(+,-) */	    default: /* case 3 */	    	    return  (z-pi_lo)-pi;/* atan(-,-) */	}}