Login or Register to Ask a Question and Join Our Community

Sponsored Content
Full Discussion: (MPI) Segmentation fault with dynamic allocated 2D array
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
 

10 More Discussions You Might Find Interesting

1. Programming

segmentation fault

hi all i'm trying to execute a c program under linux RH and it gives me segmentation fault, this program was running under unix at&t anybody kow what the problem could be? thanx in advance regards (2 Replies)
Discussion started by: omran
2 Replies

2. UNIX for Dummies Questions & Answers

Segmentation Fault

hello all, I tried a program on an array to intialise array elements from the standard input device.it is an integer array of 5 elements.but after entering the 4th element it throws a message called "Segmentation Fault" and returns to the command prompt without asking for the 5th element. ... (3 Replies)
Discussion started by: compbug
3 Replies

3. Programming

Hi! segmentation fault

I have written a program which takes a directory as command line arguments and displays all the dir and files in it. I don't know why I have a problem with the /etc directory.It displays all the directories and files untill it reaches a sub directory called peers which is in /etc/ppp/peers.the... (4 Replies)
Discussion started by: vijlak
4 Replies

4. Programming

segmentation fault

If I do this. Assume struct life { char *nolife; } struct life **life; // malloc initialization & everything if(life->nolife == 0) Would I get error at life->nolife if it is equal to 0. wrong accession? (3 Replies)
Discussion started by: joey
3 Replies

5. Programming

segmentation fault

What is segmentation fault(core dumped) (1 Reply)
Discussion started by: gokult
1 Replies

6. Programming

Segmentation fault.

I'm getting a segmentation fault. I'm new to Linux programming. Thanks so much for all of your input.:eek: #include </usr/include/mysql++/mysql++.h> #include <stdio.h> #include <iostream> #include <sstream> #include <string.h> using namespace std; int outputToImport(const char*... (1 Reply)
Discussion started by: sepoto
1 Replies

7. Programming

segmentation fault.

This code is causing a segmentation fault and I can't figure out why. I'm new to UNIX and I need to learn how to avoid this segmentation fault thing. Thank you so much. Thanks also for the great answers to my last post.:):b: int main() { mysqlpp::Connection conn(false); if... (3 Replies)
Discussion started by: sepoto
3 Replies

8. Programming

Using gdb, ignore beginning segmentation fault until reproduce environment segmentation fault

I use a binary name (ie polo) it gets some parameter , so for debugging normally i do this : i wrote script for watchdog my app (polo) and check every second if it's not running then start it , the problem is , if my app , remain in state of segmentation fault for a while (ie 15 ... (6 Replies)
Discussion started by: pooyair
6 Replies

9. Programming

Segmentation fault

I keep getting this fault on a lot of the codes I write, I'm not exactly sure why so I'd really appreciate it if someone could explain the idea to me. For example this code #include <stdio.h> main() { unsigned long a=0; unsigned long b=0; int z; { printf("Enter two... (2 Replies)
Discussion started by: sizzler786
2 Replies

10. Programming

C. To segmentation fault or not to segmentation fault, that is the question.

Oddities with gcc, 2.95.3 for the AMIGA and 4.2.1 for MY current OSX 10.14.1... I am creating a basic calculator for the AMIGA ADE *NIX emulator in C as it does not have one. Below are two very condensed snippets of which I have added the results inside the each code section. IMPORTANT!... (11 Replies)
Discussion started by: wisecracker
11 Replies

LEARN ABOUT LINUX

psc

PSC(1)							      General Commands Manual							    PSC(1)

NAME

       psc - prepare sc files

SYNOPSIS

       psc [-fLkrSPv] [-s cell] [-R n] [-C n] [-n n] [-d c]

DESCRIPTION

       Psc  is used to prepare data for input to the spreadsheet calculator sc(1).  It accepts normal ascii data on standard input.  Standard out-
       put is a sc file.  With no options, psc starts the spreadsheet in cell A0.  Strings are right justified.  All data on a line is entered	on
       the  same row; new input lines cause the output row number to increment by one.	The default delimiters are tab and space.  The column for-
       mats are set to one larger than the number of columns required to hold the largest value in the column.

OPTIONS

       -f     Omit column width calculations.  This option is for preparing data to be merged with an existing spreadsheet.  If the option is  not
	      specified, the column widths calculated for the data read by psc will override those already set in the existing spreadsheet.

       -L     Left justify strings.

       -k     Keep  all  delimiters.   This  option  causes the output cell to change on each new delimiter encountered in the input stream.   The
	      default action is to condense multiple delimiters to one, so that the cell only changes once per input data item.

       -r     Output the data by row first then column.  For input consisting of a single column, this option will result in  output  of  one  row
	      with multiple columns instead of a single column spreadsheet.

       -s cell
	      Start  the  top  left  corner  of the spreadsheet in cell.  For example, -s B33 will arrange the output data so that the spreadsheet
	      starts in column B, row 33.

       -R n   Increment by n on each new output row.

       -C n   Increment by n on each new output column.

       -n n   Output n rows before advancing to the next column.  This option is used when the input is  arranged  in  a  single  column  and  the
	      spreadsheet is to have multiple columns, each of which is to be length n.

       -d c   Use the single character c as the delimiter between input fields.

       -P     Plain numbers only.  A field is a number only when there is no imbedded [-+eE].

       -S     All numbers are strings.

       -v     Print the version of psc

SEE ALSO

       sc(1)

AUTHOR

       Robert Bond

PSC 7.16							 19 September 2002							    PSC(1)
All times are GMT -4. The time now is 06:37 PM.
Unix & Linux Forums Content Copyright 1993-2022. All Rights Reserved.
Privacy Policy