/* wheat.c -- exponential growth */
#include <stdio.h>
#define SQUARES 64    /* squares on a checkerboard   */
#define CROP 1E15     /* US wheat crop in grains     */
int main(void)
{
    double current, total;
    int count = 1;

    printf("square     grains       total     ");
    printf("fraction of \n");
    printf("           added        grains      ");
    printf("US total\n");
    total = current = 1.0; /* start with one grain   */
    printf("%4d %13.2e %12.2e %12.2e\n", count, current,
           total, total/CROP);
    while (count < SQUARES)
    {
        count = count + 1;
        current = 2.0 * current;
                     /* double grains on next square */
        total = total + current;     /* update total */
        printf("%4d %13.2e %12.2e %12.2e\n", count, current,
               total, total/CROP);
     }
     printf("That's all.\n");
   
     return 0;
}