Program to illustrate the atan( ) function

    #include <iostream.h>
    #include <math.h>                      // defines the atan( ) function
      #include <conio.h>

    void main ( )
    {
        double result ;
        double i = 0.5 ;
        result = atan ( i ) ;
        cout<<"\n The arc tangent of "<< i << " is "<< result;
        getch () ;
    }