W3School TIY Editor

#include <stdio.h> #include <math.h> int main() { printf("%f\n", atan(0.5)); printf("%f\n", atan(-0.5)); printf("%f\n", atan(5)); printf("%f\n", atan(-5.0)); printf("%f\n", atan(100.0)); printf("%f\n", atan(-100.0)); return 0; }