/* program to compute a circle's circumference and area */

#include <stdio.h>
#include <math.h> /* Provides constant M_PI */

/* calculate the circumference of a circle given its radius */
double
circumference (double radius)
{
  return 2 * M_PI * radius;
} // circum


/* calculate the area of a circle given its radius */
double
area (double radius)
{
  return M_PI * radius * radius;
} // area


/* main processing */
int
main (void)
{
  printf ("      radius   circumference   area\n");
  double radius;
  for (radius = 0; radius < 10; radius++)
    {
      printf ("%12.4lf", radius);
      printf ("%12.4lf", circumference(radius));
      printf ("%12.4lf", area(radius));
      printf ("\n");
    }
  return 0;
} // main