C Tutorial/math.h/atan

atan

Item Value Header file math.h Declaration float atanf(float arg);double atan(double arg);long double atanl(long double arg); Return returns the arc tangent of arg.

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

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