/* 
*  File: pi-c.c
*  Purpose: Estimates pi using the Leibniz formula (in C).
*  Compile: gcc -o pi-c pi-c.c -lm
*  Run: ./pi-c
*/
#include <stdio.h>
#include <math.h>
#include <time.h>

/* We define pi here so we can check and see how accurate our computation is. */
#define PI 3.141592653589793238462643

int main(int argc, char **argv) {
	int intervals;
	printf("Number of intervals: ");
	fflush(stdout);
	scanf("%d", &intervals);

	clock_t time1 = clock();

	int i;
	double sum, total = 0;
	for (i = 0; i < intervals; ++i) {
		total += pow(-1, i) / (2 * i + 1);
	}

	clock_t time2 = clock();
	
	total = total * 4;
	printf("Result: %.10lf\n", total);
	printf("Accuracy: %.10lf\n", PI - total);
	printf("Time:	%.10lf\n", (double)(time2 - time1)/CLOCKS_PER_SEC);
}