我是并行编程的新手，我的项目是在C编程语言中使用mpi进行二维矩阵矢量乘法。我有这个乘法功能，但是我不知道如何使用mpi来运行它。你能帮我吗？
我写这些命令，
$ mpicc -g -Wall -o matrix2d matrix2d.c -lm -c
$ mpiexec ./matrix2d.c
但是我遇到一些错误。
mpiexec was unable to launch the specified application as it could not access
or execute an executable:
Executable: ./matrix2d
Node: ubuntu
while attempting to start process rank 0.
2D矩阵-向量乘法功能在下面：
#include <stdio.h>
#include <stdlib.h>
#include <mpi.h>
#include <math.h>
void* MatrixVectorMultiply_2D(int n, double *a, double *b, double *x, MPI_Comm comm)
{
int ROW=0, COL=1; /* Improve readability */
int i, j, nlocal;
double *px; /* Will store partial dot products */
int npes, dims[2], periods[2], keep_dims[2];
int myrank, my2drank, mycoords[2];
int other_rank, coords[2];
MPI_Status status;
MPI_Comm comm_2d, comm_row, comm_col;
/* Get information about the communicator */
MPI_Comm_size(comm, &npes);
MPI_Comm_rank(comm, &myrank);
/* Compute the size of the square grid */
dims[ROW] = dims[COL] = sqrt(npes);
nlocal = n/dims[ROW];
/* Allocate memory for the array that will hold the partial dot-products */
px = malloc(nlocal*sizeof(double));
/* Set up the Cartesian topology and get the rank & coordinates of the process in
this topology */
periods[ROW] = periods[COL] = 1; /* Set the periods for wrap-around connections */
MPI_Cart_create(MPI_COMM_WORLD, 2, dims, periods, 1, &comm_2d);
MPI_Comm_rank(comm_2d, &my2drank); /* Get my rank in the new topology */
MPI_Cart_coords(comm_2d, my2drank, 2, mycoords); /* Get my coordinates */
/* Create the row-based sub-topology */
keep_dims[ROW] = 0;
keep_dims[COL] = 1;
MPI_Cart_sub(comm_2d, keep_dims, &comm_row);
/* Create the column-based sub-topology */
keep_dims[ROW] = 1;
keep_dims[COL] = 0;
MPI_Cart_sub(comm_2d, keep_dims, &comm_col);
/* Redistribute the b vector. */
/* Step 1. The processors along the 0th column send their data to the diagonal
processors */
if (mycoords[COL] == 0 && mycoords[ROW] != 0) { /* I'm in the first column */
coords[ROW] = mycoords[ROW];
coords[COL] = mycoords[ROW];
MPI_Cart_rank(comm_2d, coords, &other_rank);
MPI_Send(b, nlocal, MPI_DOUBLE, other_rank, 1, comm_2d);
}
if (mycoords[ROW] == mycoords[COL] && mycoords[ROW] != 0) {
coords[ROW] = mycoords[ROW];
coords[COL] = 0;
MPI_Cart_rank(comm_2d, coords, &other_rank);
MPI_Recv(b, nlocal, MPI_DOUBLE, other_rank, 1, comm_2d,
&status);
}
/* Step 2. The diagonal processors perform a column-wise broadcast */
coords[0] = mycoords[COL];
MPI_Cart_rank(comm_col, coords, &other_rank);
MPI_Bcast(b, nlocal, MPI_DOUBLE, other_rank, comm_col);
/* Get into the main computational loop */
for (i=0; i<nlocal; i++) {
px[i] = 0.0;
for (j=0; j<nlocal; j++) {
px[i] += a[i*nlocal+j]*b[j];
}
}
/* Perform the sum-reduction along the rows to add up the partial dot-products */
coords[0] = 0;
MPI_Cart_rank(comm_row, coords, &other_rank);
MPI_Reduce(px, x, nlocal, MPI_DOUBLE, MPI_SUM, other_rank,
comm_row);
MPI_Comm_free(&comm_2d); /* Free up communicator */
MPI_Comm_free(&comm_row); /* Free up communicator */
MPI_Comm_free(&comm_col); /* Free up communicator */
free(px);
MPI_Finalize();
我刚刚解决了之前的问题，但是现在我遇到了另一个错误，但仍然无法摆脱。拜托，有人可以帮我吗？
我运行此命令：
mpiexec -np 7 ./matrix2d.c ./matrix2d
但是我遇到了另一个错误。
Open MPI tried to fork a new process via the "execve" system call but
failed. Open MPI checks many things before attempting to launch a
child process, but nothing is perfect. This error may be indicative
of another problem on the target host, or even something as silly as
having specified a directory for your application. Your job will now
abort.
Local host: ubuntu
Application name: ./matrix2d.c
Error: Exec format error
--------------------------------------------------------------------------
7 total processes failed to start
[ubuntu:83710] 6 more processes have sent help message help-orte-odls-
default.txt / execve error
[ubuntu:83710] Set MCA parameter "orte_base_help_aggregate" to 0 to see all
help / error messages
是什么意思？我在哪里做错了？
谢谢你，谢谢。