[~/Code/test/ANSI C/] % cat sin.c #include <stdio.h> #include <math.h> int main() { double d = 43998769152.000000; printf("%16le\n",sin(d)); printf("%16le\n",sin(43998769152.000000)); } [~/Code/test/ANSI C/] % gcc -o sin sin.c -lm;./sin -4.081937e-09 -4.025292e-09