#include <stdio.h>
double ComputePI()
{
	int segment		= 16 * 256;
	double length		= 1.0;
	double segment_width	= length / segment;
	double sum		= 0.0;
	int step 		= 0;
	double pos 		= 0.0;
 
	for (step = 0; step < segment; step++)
	{
		pos = (step + 0.5) * segment_width;
 
		sum += 4 / (1 + pos * pos);
	}
 
	sum *= segment_width;
 
	return sum;
}
 
int main(int argc, char *argv[])
{
	double pi = ComputePI();
	printf("PI is %f\n", pi);
 
	return 0;
}