MPI

/* dmocek */

#include "mpi.h"
#include <stdio.h>
#include <math.h>

void main(int argc, char *argv[])
{
    int done = 0, n, numprocs, i;
    double PI25DT = 3.141592653589793238462643;
    double mypi, pi, h, sum, x;
    double startwtime, endwtime;
    int  namelen;
    char processor_name[MPI_MAX_PROCESSOR_NAME];
    double w[8];
    double recv_data;
    int t;
    int mytid;
    double a,c ;
    MPI_Status b;

    MPI_Init(&argc,&argv);
    MPI_Comm_size(MPI_COMM_WORLD,&numprocs);
    MPI_Comm_rank(MPI_COMM_WORLD,&mytid);
    MPI_Get_processor_name(processor_name,&namelen);

    fprintf(stderr,"Process %d on %s\n", mytid, processor_name);
    fflush(stderr);

    if(mytid == 0) {
        printf("Podaj 8 wartosci: \n");
        fflush(stdout);
        scanf("%lf %lf %lf %lf %lf %lf %lf %lf", &w[0], &w[1], &w[2], &w[3], &w[4], &w[5], &w[6], &w[7]);
        printf("Podaj wartosc t:\n");
        scanf("%d", &t);
    }

    MPI_Scatter(w, 1, MPI_DOUBLE, &recv_data, 1, MPI_DOUBLE, 0, MPI_COMM_WORLD);
    MPI_Bcast(&t, 1, MPI_INT, 0, MPI_COMM_WORLD);

    for(i = 0; i < t; i++) {
        // send
        // wyslij w prawo
        if(mytid == 0) {
                                                // 6345 + 1
            MPI_Send(&recv_data, 1, MPI_DOUBLE, mytid + 1, 0, MPI_COMM_WORLD);
        }
        // wyslij w lewo
        else if(mytid == 7) {
                                                // 7869 - 1
            MPI_Send(&recv_data, 1, MPI_DOUBLE, mytid - 1, 0, MPI_COMM_WORLD);
        }
        // wyslij prawo i lewo
        else {
            MPI_Send(&recv_data, 1, MPI_DOUBLE, mytid + 1, 0, MPI_COMM_WORLD);
            MPI_Send(&recv_data, 1, MPI_DOUBLE, mytid - 1, 0, MPI_COMM_WORLD);
        }


        // recv
        if(mytid == 0) {
            MPI_Recv(&a, 1, MPI_DOUBLE, mytid + 1, 0, MPI_COMM_WORLD, &b);
            c=0;
        }
        else if(mytid == 7) {
            MPI_Recv(&a, 1, MPI_DOUBLE, mytid - 1, 0, MPI_COMM_WORLD, &b);
            c=0;
        }
        else {
            MPI_Recv(&a, 1, MPI_DOUBLE, mytid - 1, 0, MPI_COMM_WORLD, &b);
            MPI_Recv(&c, 1, MPI_DOUBLE, mytid + 1, 0, MPI_COMM_WORLD, &b);
        }
//      MPI_Barrier(MPI_COMM_WORLD);

        recv_data = (a + 2*recv_data + c) / 4;
    }

    MPI_Gather(&recv_data, 1, MPI_DOUBLE, w, 1, MPI_DOUBLE, 0, MPI_COMM_WORLD);
    printf("-------PID: %d---------\n", mytid);
    printf("recv_data = %lf\n", recv_data);

    printf("w = ");
    for(i = 0; i < 8; i++)
        printf("%lf ", w[i]);
    printf("\n");
    MPI_Finalize();
}