Addded integration

integration/integration.cpp

+#include <cstdio>
+#include <mpi.h>
+
+int main()
+{
+	MPI_Comm comm;
+	int size, rank;
+
+	MPI_Init(NULL, NULL); comm = MPI_COMM_WORLD;
+    MPI_Comm_rank(comm, &rank); 
+    MPI_Comm_size(comm, &size);
+
+	const int totalsteps = 10000;
+	const int steps = totalsteps/size;
+
+	const double dx = 1./totalsteps;
+
+	int ini = rank * steps;
+    int fin = (rank+1) * steps;
+
+    if(fin >= totalsteps)
+        fin = totalsteps;
+
+    double localSum = 0.0;
+    for(int i=ini; i<fin; i++)
+    {
+        double x = (i-0.5) * dx;
+        localSum += 4.0 / (1.0 + x*x);
+    }
+
+    localSum = localSum * dx;
+
+    double globalSum = 0.0;
+    MPI_Allreduce(&localSum,&globalSum,1,MPI_DOUBLE_PRECISION,MPI_SUM,comm);
+
+	printf("%f %f\n", localSum, globalSum);
+
+    MPI_Barrier(comm);
+    MPI_Finalize();
+
+	return 0;
+}
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integration/integration.f90

+program integration
+    implicit none
+    include 'mpif.h'
+   
+    integer ierr, comm, rank, size
+    integer i, totalsteps, steps, ini, fin
+    double precision dx, x, localSum, globalSum
+     
+    call MPI_INIT(ierr); comm = MPI_COMM_WORLD
+    
+    call MPI_COMM_RANK(comm, rank, ierr)
+    call MPI_COMM_SIZE(comm, size, ierr)
+
+    totalsteps = 1000000
+    steps = totalsteps/size
+
+    ini = rank * steps
+    fin = (rank+1) * steps
+
+    if(fin.ge.totalsteps) then
+        fin = totalsteps
+    endif
+
+    write(*,*) rank, ini, fin
+
+    dx = 1.d0 / totalsteps
+    x = -0.5d0 * dx
+
+    localSum = 0.d0
+    do i = ini, fin
+        x = (i-0.5d0)*dx
+        localSum = localSum + 4.d0 / (1.d0 + x*x)
+    enddo
+    localSum = localSum * dx
+
+    call MPI_ALLREDUCE(localSum,globalSum,1,MPI_DOUBLE_PRECISION,MPI_SUM,comm,ierr)
+
+    write(*,*) localSum, globalSum
+
+    call MPI_BARRIER(comm,ierr)
+    call MPI_FINALIZE(ierr)
+end program integration
+           
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integration/integration.py

+from mpi4py import MPI
+import numpy
+
+comm = MPI.COMM_WORLD
+rank = comm.Get_rank()
+size = comm.Get_size()
+
+totalsteps = 1000000
+steps = totalsteps/size
+
+ini = rank * steps
+fin = (rank+1) * steps
+
+if fin > totalsteps:
+	fin = totalsteps
+
+print(rank, ini, fin)
+
+dx = 1./totalsteps
+x = -0.5*dx
+
+localSum = 0.
+for i in range(int(ini), int(fin)):
+	x = (i-0.5)*dx
+	localSum = localSum + 4./(1. + x*x)
+
+localSum = localSum * dx
+
+globalSum = comm.allreduce(localSum, op=MPI.SUM)
+
+print(localSum, globalSum)
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