#include <stdio.h>
#include <string.h>
//#include "mpi.h"

#include <math.h>

#include <sys/time.h>
//#include <time.h>


int main(int argc, char** argv)
{
    long n, i;
    double total;
    struct timeval tv;
    struct timezone tz;
    long starttimeSec, starttimeMicro;
    long endtimeSec, endtimeMicro;
    long totalSec, totalMicro;

    
//    MPI_Init( &argc, &argv );

    if (argc > 1)
       n = atoi(argv[1]);
    else
       n = 1000;
    
    gettimeofday(&tv, &tz);
    starttimeSec = tv.tv_sec;
    starttimeMicro = tv.tv_usec;
    printf("Time(0)=%d sec %d microsec\n", starttimeSec, starttimeMicro);
    
    
//    printf("Time(0)=%u\n", time(0));

    total = 0.0;
    for(i = 1; i <= n; i++)
    {
        if(i % 4 == 1)
        {
            total += 1.0 / i;
        }
        else if (i % 4 == 3)
        {
            total -= 1.0 / i;
        }
    }

    gettimeofday(&tv, &tz);
    endtimeSec = tv.tv_sec;
    endtimeMicro = tv.tv_usec;
    printf("Time = %d sec %d microsec\n", endtimeSec, endtimeMicro);
    
    if (endtimeSec > starttimeSec)
    {
        totalSec = endtimeSec-starttimeSec;
	totalMicro = endtimeMicro + (1000000 - starttimeMicro);
    }
    else {
        totalSec = 0;
	totalMicro = endtimeMicro - starttimeMicro;
    }


 //   printf("Time(0)=%u\n", ftime(0));
    printf("Pi = %.32f for %d iterations.\n", total * 4, n);
    printf("Real PI = %.32lf\n", M_PI);
    printf("Percent error = %.32lf\n", fabs((total*4)-M_PI)/M_PI * 100); 
    printf("Time: %d sec and %d microsec\n", totalSec, totalMicro);
//    MPI_Finalize();
    return 0;
}

/*

gcc -o  calculatePi.c 
./calculatePi 100000000
Time(0)=1051631280 sec 105197 microsec
Time = 1051631287 sec 82038 microsec
Pi = 3.14159263359032303597473401168827 for 100000000 iterations.
Real PI = 3.14159265358979311599796346854419
Percent error = 0.00000063660290449083210968897776
Time: 7 sec and 976841 microsec
*/