--- [プログラム 3] pi.c

    1	/* http://www.cs.gsu.edu/~cscyip/csc4310/pi_openmp.doc より*/
    2	#include <stdio.h>
    3	#include <stdlib.h>
    4	
    5	//#define num_steps 500000000
    6	#define num_steps 100000000
    7	double step;
    8	main ()
    9	{int i;
   10	     double x, pi, s = 0.0;
   11	     step = 1.0/(double) num_steps;
   12	#pragma omp parallel for private(x) reduction(+:s)
   13	     for (i=1;i<= num_steps; i++){
   14	     	 x = (i-0.5)*step;
   15		 s += 4.0/(1.0+x*x);
   16	     }
   17	     pi = step * s;
   18	     printf (" pi = %.15e \n",pi);
   19	}
   20	
--- END
