			! This exercise is taken from the class Parallel Programming Workshop (MPI,
			! OpenMP and Advanced Topics) at HLRS given by Rolf Rabenseifner

			program compute_pi
			implicit none

			! times using cpu_time
			real t0,t1
			!--unused-- use omp_lib
			!$ double precision omp_get_wtime
			!$ double precision wt0,wt1

			integer nthreads
			integer i
			integer, parameter :: n=10000000
			real(kind=8) w,x,sum,pi,f,a

			! function to integrate
			f(a) = 4.0_8 / (1.0_8 + a * a)

			! Begin of SPACE for FIRST EXERCISE


			! End of SPACE for FIRST EXERCISE

			!$ wt0=omp_get_wtime()
			call cpu_time(t0)

			! calculate pi = integral [0..1] 4/(1+x**2) dx
			w = 1.0_8 / n
			sum = 0.0_8
			do i=1,n
			x= w * (i-0.5_8)
			sum=sum+f(x)
			enddo
			pi=w*sum

			call cpu_time(t1)
			!$ wt1=omp_get_wtime()

			write (*,'(/,a,1pg24.16)') 'computed pi = ', pi
			write (*,'(/,a,1pg12.4)') 'cpu_time: ', t1-t0
			!$ write (*,'(/,a,1pg12.4)') 'omp_get_wtime:', wt1-wt0
			stop
			end program compute_pi

scitas-intro-to-parallelism/openmp/pi.f90
82af3a6be261complete

pi.f90
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