P4 = -1.65339022054652515390e-06, /* 0xBEBBBD41, 0xC5D26BF1 */
P5 = 4.13813679705723846039e-08; /* 0x3E663769, 0x72BEA4D0 */
-static volatile double
+static const volatile double
twom1000 = 9.33263618503218878990e-302; /* 2**-1000=0x01700000,0 */
double exp(double x)