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Top Forums Programming (MPI) Segmentation fault with dynamic allocated 2D array Post 302150646 by lancer6238 on Wednesday 12th of December 2007 04:04:42 AM
Old 12-12-2007
(MPI) Segmentation fault with dynamic allocated 2D array

Hi all,
I'm getting segmentation fault errors when I try to send/receive 2 rows of a matrix as a block, and I can't figure out why.

Basically, I have a 4x5 matrix with an extra top row and an extra leftmost column, making it a (4+1)x(5+1) matrix stored in P0. I'm trying to send the 2nd and 3rd row as a block to P1, print out the contents, send the 4th and 5th row as a block to P1, then print out the contents again. I have dynamically allocated a (4+1)x(5+1) memory block to cellblock, then used the pointers cell[i] to point to each "row" of cellblock, so I can access the 2D array by cell[i][j].

I get the correct output, but with segmentation fault at the end.

Here is my code:

Code:
#include <stdio.h>
#include <stdlib.h>
#include <mpi.h>

int main(int argc, char** argv)
{
   int rank, i, j, k = 1;
   int **cell, *row1, *cellblock;
   MPI_Status status;
   MPI_Init(&argc, &argv);
   MPI_Comm_rank(MPI_COMM_WORLD, &rank);
   row1 = (int*)calloc((5+1) * 2, sizeof(int));
   cellblock = (int*)calloc((4+1)*(5+1), sizeof(int));
   cell = &cellblock;
   for (i = 0 ; i < (4+1) ; i++)
        cell[i] = &cellblock[i*(5+1)];
   if (rank == 0)
   {
        for (i = 0 ; i < (4+1) ; i++)
              for (j = 0 ; j < (5+1) ; j++)
                   cell[i][j] = k++;
        for (i = 1 ; i < 5 ; i+=2)
              MPI_Send(&(cell[i][0]), (5+1)*2, MPI_INT, 1, 1, MPI_COMM_WORLD);
   }
   if (rank == 1)
   {
        for (i = 0 ; i < 2 ; i++)
        {
            MPI_Recv(row1, (5+1)*2, MPI_INT, 0, 1, MPI_COMM_WORLD, &status);
            for (j = 0 ; j < (5+1)*2 ; j++)
                printf("%d ", row1[j]);
            printf("\n");
       }
   }
   free(row1);
   free(cellblock);
   MPI_Finalize();
   return 0;

}

Please advise. Thank you.

Regards,
Rayne
 

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TableMatrix::Spreadsheet(3pm)				       perl/Tk Documentation				     TableMatrix::Spreadsheet(3pm)

NAME
Tk::TableMatrix::Spreadsheet - Table Display with Spreadsheet-like bindings. SYNOPSIS
use Tk; use Tk::TableMatrix::Spreadsheet; my $t = $top->Scrolled('Spreadsheet', -rows => 21, -cols => 11, -width => 6, -height => 6, -titlerows => 1, -titlecols => 1, -variable => $arrayVar, -selectmode => 'extended', -titlerows => 1, -titlecols => 1, -bg => 'white', ); DESCRIPTION
Tk::TableMatrix::Spreadsheet is a Tk::TableMatrix-derived widget that implements some bindings so the resulting widget behaves more like a spreadsheet. Bindings Added: o Row/Col resize handles appear when the cursor is placed over a row/col border line in the rol/col title area. Dragging these handles will resize the row or column. If multiple rows or columns are selected, then the new row/col size will apply to all row/cols selected. Note: With the base Tk::TableMatrix, it is possible to resize the row/cols by dragging on any cell border. To be more spreadsheet-like, Tk::TableMatrix::Spreadsheet defaults to enable row/col resizing only thru the title row/col dragging. To override this default behavoir, set the -resizeborder option to 'both' at startup. o A popup menu for row/col insert/delete appears when the mouse is right-clicked in the row/col title areas. o Cells activate (i.e. the contents become edit-able) only when the cell is double-clicked or the F2 button is pressed. The default Tk::TableMatrix behavior is for the cell to be activated when the cell is single-clicked. o The Escape key causes any changes made to a cell to be canceled and the current selection cleared. o The return key causes the the current cell to move down. o The tab (or shift tab) key causes the current cell to be moved to the right (left). o The delete key will delete the current selection, if no cell is currently active. o The Mouse button 2 (middle button) paste from the PRIMARY. (Control-v pastes from the clipboard). Additional Information Widget methods, options, etc, are inherited from the Tk::TableMatrix widget. See its docs for additional information. Tk1.23 2007-01-09 TableMatrix::Spreadsheet(3pm)
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