C Tutorial/math.h/atan2

atan2

Item Value Header file math.h Declaration float atan2f(float a, float b);double atan2(double a, double b);long double atan2l(long double a, long double b); Return returns the arc tangent of a/b.

<source lang="cpp">#include <math.h>

 #include <stdio.h>
 int main(void)
 {
   double val = -1.0;
   do {
     printf("Atan2 of %f is %f.\n", val, atan2(val,1.0));
     val += 0.1;
   } while(val<=1.0);
   return 0;
 }</source>