/**********************************************************
 * File: cpi_serial.c
 * Purpose: Serial computation of pi in C with measurement 
 *          of the time taken to complete the computation.
 **********************************************************/
#include <stdio.h> 
#include <time.h>

int main() {
  int n = 4800000, i, sp, ep;
  double pi, h, sum = 0.0, x, time;
  clock_t st, et;

  sp = 1;
  ep = n;

  st = clock();  // get the start time of the pi computation 
  h = 1.0 / n;
  for(i=sp; i<=ep; i++) {
    x = h * (i-0.5);
    sum = sum + 4.0/(1.0+x*x);
  }
  pi = h * sum;
  et = clock();  // get the end time of the pi computation 

  printf("pi: %.16f\n", pi);
  printf("execution time: %.6f sec\n", (double)(et-st)/(double)CLOCKS_PER_SEC);

  return 0;
}