/*
 *  ===========================================================================
 *  Compute Area of a Circle : Coefficients are defined in main program.
 *                           : Radius and area of circle are printed to screen.
 *                                                                     
 *  Written by: M.A. Austin                                       January, 1994
 *  ===========================================================================
 */

#include <stdio.h>   /* Standard Input/Output function declarations        */
#include <math.h>    /* Math functions, such as sqrt(x), and constant M_PI */

int main( void ) {
 float fRadius; /* Radius of circle  */
 float   fArea; /* Area of circle    */
 float     fPi; /* Variable for "pi" */

 /* [a] : Initialize Radius and pi */

    fRadius = 2.0;
    fPi     = 4.0*atan( 1.0 );

 /* [b] : Compute Area of Circle */

    fArea   = fPi*fRadius*fRadius;

 /* [c] : Print Welcome Message */

    printf("Compute Area of Circle with Predefined Radius \n");
    printf("============================================= \n");

 /* [d] : Print Radius and Area */

    printf("Radius of Circle = %12.7f \n", fRadius );
    printf("Area of Circle   = %12.7f \n", fArea );

}