C/math.h/atan

atan: returns the arc tangent of arg

<source lang="cpp">

//Declaration: float atanf(float arg);

              double atan(double arg); 
              long double atanl(long double arg);  

 
 #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;
 }
        

/* Arc tangent of -1.000000 is -0.785398. Arc tangent of -0.900000 is -0.732815. Arc tangent of -0.800000 is -0.674741. Arc tangent of -0.700000 is -0.610726. Arc tangent of -0.600000 is -0.540420. Arc tangent of -0.500000 is -0.463648. Arc tangent of -0.400000 is -0.380506. Arc tangent of -0.300000 is -0.291457. Arc tangent of -0.200000 is -0.197396. Arc tangent of -0.100000 is -0.099669. Arc tangent of 0.000000 is 0.000000. Arc tangent of 0.100000 is 0.099669. Arc tangent of 0.200000 is 0.197396. Arc tangent of 0.300000 is 0.291457. Arc tangent of 0.400000 is 0.380506. Arc tangent of 0.500000 is 0.463648. Arc tangent of 0.600000 is 0.540420. Arc tangent of 0.700000 is 0.610726. Arc tangent of 0.800000 is 0.674741. Arc tangent of 0.900000 is 0.732815. Arc tangent of 1.000000 is 0.785398.

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      </source>