if(x > o_threshold) return huge*huge;
if(x > o_threshold) return really_big*really_big;
	double fd_expm1(double x)#else	double fd_expm1(x)	double x;#endif{	double y,hi,lo,c,t,e,hxs,hfx,r1;	int k,xsb;	unsigned hx;	hx  = __HI(x);	/* high word of x */	xsb = hx&0x80000000;		/* sign bit of x */	if(xsb==0) y=x; else y= -x;	/* y = |x| */	hx &= 0x7fffffff;		/* high word of |x| */    /* filter out huge and non-finite argument */	if(hx >= 0x4043687A) {			/* if |x|>=56*ln2 */	    if(hx >= 0x40862E42) {		/* if |x|>=709.78... */                if(hx>=0x7ff00000) {		    if(((hx&0xfffff)|__LO(x))!=0) 		         return x+x; 	 /* NaN */		    else return (xsb==0)? x:-1.0;/* exp(+-inf)={inf,-1} */	        }	        if(x > o_threshold) return huge*huge; /* overflow */	    }	    if(xsb!=0) { /* x < -56*ln2, return -1.0 with inexact */		if(x+tiny<0.0)		/* raise inexact */		return tiny-one;	/* return -1 */	    }	}    /* argument reduction */	if(hx > 0x3fd62e42) {		/* if  |x| > 0.5 ln2 */ 	    if(hx < 0x3FF0A2B2) {	/* and |x| < 1.5 ln2 */		if(xsb==0)		    {hi = x - ln2_hi; lo =  ln2_lo;  k =  1;}		else		    {hi = x + ln2_hi; lo = -ln2_lo;  k = -1;}	    } else {		k  = (int)(invln2*x+((xsb==0)?0.5:-0.5));		t  = k;		hi = x - t*ln2_hi;	/* t*ln2_hi is exact here */		lo = t*ln2_lo;	    }	    x  = hi - lo;	    c  = (hi-x)-lo;	} 	else if(hx < 0x3c900000) {  	/* when |x|<2**-54, return x */	    t = huge+x;	/* return x with inexact flags when x!=0 */	    return x - (t-(huge+x));		}	else k = 0;    /* x is now in primary range */	hfx = 0.5*x;	hxs = x*hfx;	r1 = one+hxs*(Q1+hxs*(Q2+hxs*(Q3+hxs*(Q4+hxs*Q5))));	t  = 3.0-r1*hfx;	e  = hxs*((r1-t)/(6.0 - x*t));	if(k==0) return x - (x*e-hxs);		/* c is 0 */	else {	    e  = (x*(e-c)-c);	    e -= hxs;	    if(k== -1) return 0.5*(x-e)-0.5;	    if(k==1) 	       	if(x < -0.25) return -2.0*(e-(x+0.5));	       	else 	      return  one+2.0*(x-e);	    if (k <= -2 || k>56) {   /* suffice to return exp(x)-1 */	        y = one-(e-x);	        __HI(y) += (k<<20);	/* add k to y's exponent */	        return y-one;	    }	    t = one;	    if(k<20) {	       	__HI(t) = 0x3ff00000 - (0x200000>>k);  /* t=1-2^-k */	       	y = t-(e-x);	       	__HI(y) += (k<<20);	/* add k to y's exponent */	   } else {	       	__HI(t)  = ((0x3ff-k)<<20);	/* 2^-k */	       	y = x-(e+t);	       	y += one;	       	__HI(y) += (k<<20);	/* add k to y's exponent */	    }	}	return y;}