__HI(x) = hx;
u.d = x; __HI(u) = hx; x = u.d;
	double __ieee754_log10(double x)#else	double __ieee754_log10(x)	double x;#endif{	double y,z;	int i,k,hx;	unsigned lx;	hx = __HI(x);	/* high word of x */	lx = __LO(x);	/* low word of x */        k=0;        if (hx < 0x00100000) {                  /* x < 2**-1022  */            if (((hx&0x7fffffff)|lx)==0)                return -two54/zero;             /* log(+-0)=-inf */            if (hx<0) return (x-x)/zero;        /* log(-#) = NaN */            k -= 54; x *= two54; /* subnormal number, scale up x */            hx = __HI(x);                /* high word of x */        }	if (hx >= 0x7ff00000) return x+x;	k += (hx>>20)-1023;	i  = ((unsigned)k&0x80000000)>>31;        hx = (hx&0x000fffff)|((0x3ff-i)<<20);        y  = (double)(k+i);        __HI(x) = hx;	z  = y*log10_2lo + ivln10*__ieee754_log(x);	return  z+y*log10_2hi;}