Monte Carlo

/* Montecarlo */
/* integration using monte carlo */
/* by counting relative areas */
/* integrates y=x^2 to your specified limits */
#define _CRT_SECURE_NO_WARNINGS
#include <stdio.h>
#include <stdlib.h>
#include <math.h>
main()
{
    double x, y;
    double yupper, ylower, xupper, xlower;
    double montearea, area;
    double totalexparea, totalarea;
int j;
  int iterations;
     printf("enter lower limit\n");
        scanf("%lf", &xlower);
          printf("enter upper limit\n");
            scanf("%lf", &xupper);
printf("xlower %lf xupper %lf\n", xlower, xupper);
    yupper = pow(xupper, 2);
    ylower = pow(xlower, 2);
      printf("ylower %lf yupper %lf\n", ylower, yupper);
area = yupper * (xupper - xlower);
    printf("outer area is %lf\n", area);
       printf("enter iterations \n");
        scanf("%d", &iterations);
        totalarea = 0;
        totalexparea = 0;
for (j = 1;j < iterations;j++)
{
    x = rand() % 1000;/* generate random number for x up to 1000 */
    y = rand() % 1000;/* generate random number for y up to 1000 */
        y = y / 1000;/* Divide by 1000 so our number is between 0 and 1 */
        x = x / 1000;/* Divide by 1000 so our number is between 0 and 1 */
          x = xlower + (xupper - xlower)*x;/* Adjust x value to be between required limits */

y = yupper * y;/* Adjust y value to be between required limits */

if (x >= xlower)
{
    totalarea = totalarea + 1;/* add 1 to count of points within whole area */
    
    /* test if this y value is below the curve */

if (y <= pow(x, 2))
{

   totalexparea = totalexparea + 1;/* add 1 to count of points below the curve */
}

}
}

if (totalarea != 0)
{
  montearea = area * (totalexparea / totalarea);/* calculate the area below the curve */
}
  printf("monte area is %lf\n", montearea);
}