#include<mpi.h>
#include<stdio.h>

float fn(float x)
{
	return x*x;
}

float compute(float a,float b,float h)
{
	int cnt = 0;
	float to_return = 0.0;
	while(a<=b)
	{	
		if(cnt%2)
		to_return += 4*fn(a);
		else
		to_return += 2*fn(a);
		cnt++;
		a += h;
	}
	return to_return;
}

int main(int argc,char *argv[])
{
	int size,rank;
	float a,b,n,h;
	float local,global;
	a = 1;
	b = 3;
	n = 10000;
	MPI_Status status;
	MPI_Init(&argc,&argv);	
	MPI_Comm_size(MPI_COMM_WORLD,&size);
	MPI_Comm_rank(MPI_COMM_WORLD,&rank);
	h = (b-a)/n;

	local = (h*compute(a+(rank*n*h)/size,a+((rank+1)*n*h)/size,h))/3.0;
	//printf("%f %f\n",h,local);
	MPI_Reduce(&local,&global,1,MPI_FLOAT,MPI_SUM,0,MPI_COMM_WORLD);
	
	if(rank == 0)
	{
		printf("%f",global);
	}	
	MPI_Finalize();	
		
	return 0;
}