#include <stdio.h>
#include <math.h>

double f1(double x)
{
   return x * x; 
}

double midpoint_rule(double a, double b, int n, double (*func)(double))
{
   double s, fa, fb, x, h;
   int j;

   h = (b-a)/((double) n);
   s=0.0;

   for (j=0; j < n; j++)
   {
      x = a + (j+0.5) * h;
      s += (*func)(x);
   }
   s *= h;

   return s;
} 

int main()
{
   int n;
   double a=0.0, b=2.0;
   
   printf("Number of partitions = ");
   scanf("%d", &n) ;
   
   printf("f1  = %lf\n", midpoint_rule(a, b, n, f1)) ;
   
   return 0;
}