25 scalb64(__float64 x, __float64 fn)  in scalb64()  argument
27     if (isnan(fn) || isnan(x))  in scalb64()
28         return x + fn;  in scalb64()
30     if (isinf(fn)) {  in scalb64()
31         if ((x == 0.0 && fn > 0.0) || (isinf(x) && fn < 0.0))  in scalb64()
32             return __math_invalid(fn);  in scalb64()
33         if (fn > 0.0)  in scalb64()
34             return fn*x;  in scalb64()
36             return x/(-fn);  in scalb64()
39     if (rint64(fn) != fn)  in scalb64()
40         return __math_invalid(fn);  in scalb64()
42     if (fn > 4 * _FLOAT64_MAX_EXP)  in scalb64()
43         fn = 4 * _FLOAT64_MAX_EXP;  in scalb64()
45     if (fn < -4 * _FLOAT64_MAX_EXP)  in scalb64()
46         fn = -4 * _FLOAT64_MAX_EXP;  in scalb64()
48     return scalbn64(x, (int)fn);  in scalb64()