[petsc-users] Trouble with solving 5x5 system... Ay=x on 2 or more processors

[Shri]

You are not setting the 'global' and the 'local' sizes of vector x correctly as the error message says. The global size of the matrix is 5X5 while the global size of the vector x is 10 !!! 
----- Original Message -----


Hi, 

I am trying to solve a linear system where Ay=x and A is a 5x5 matrix stored in a binary file called 'square' and x=[1;1;1;1;1] 

I am trying to display the matrix A, and the vectors x(rhs) and y(soln) in that order to standard output. 

On running my code on a single processor the answer returned is accurate. But on using 2 processors I get weird error messages PART of which says 

[0]PETSC ERROR: [1]PETSC ERROR: --------------------- Error Message ------------------------------------ 
[1]PETSC ERROR: Nonconforming object sizes! 
[1]PETSC ERROR: Mat mat,Vec x: global dim 5 10! 

Also somehow the vector x gets displayed TWICE when run on two processes. A however gets displayed ONCE (as it should!!) 


I am attaching the output I get when I run on 1 process and the when I run the same code on 2 processes. 
please let me know where I could be going wrong. 

(1) 

This is what I get on running on ONE process: (Here system is solved successfully) 

gaurish108 at gaurish108-laptop:~/Desktop$ $PETSC_DIR/$PETSC_ARCH/bin/mpiexec -n 1 ./ex4 -f square 

1.5761308167754828e-01 1.4188633862721534e-01 6.5574069915658684e-01 7.5774013057833345e-01 7.0604608801960878e-01 
9.7059278176061570e-01 4.2176128262627499e-01 3.5711678574189554e-02 7.4313246812491618e-01 3.1832846377420676e-02 
9.5716694824294557e-01 9.1573552518906709e-01 8.4912930586877711e-01 3.9222701953416816e-01 2.7692298496088996e-01 
4.8537564872284122e-01 7.9220732955955442e-01 9.3399324775755055e-01 6.5547789017755664e-01 4.6171390631153941e-02 
8.0028046888880011e-01 9.5949242639290300e-01 6.7873515485777347e-01 1.7118668781156177e-01 9.7131781235847536e-02 
Process [0] 
1 
1 
1 
1 
1 
KSPGetIterationNumber 5 
KSPGetResidualNorm 0.000000 
Process [0] 
-0.810214 
2.33178 
-1.31131 
1.09323 
1.17322 
gaurish108 at gaurish108-laptop:~/Desktop$ 

%-------------------------------------------------------------------- 
This is what I get on running on TWO processes: 

(2) 

gaurish108 at gaurish108-laptop:~/Desktop$ $PETSC_DIR/$PETSC_ARCH/bin/mpiexec -n 2 ./ex4 -f square 
1.5761308167754828e-01 1.4188633862721534e-01 6.5574069915658684e-01 7.5774013057833345e-01 7.0604608801960878e-01 
9.7059278176061570e-01 4.2176128262627499e-01 3.5711678574189554e-02 7.4313246812491618e-01 3.1832846377420676e-02 
9.5716694824294557e-01 9.1573552518906709e-01 8.4912930586877711e-01 3.9222701953416816e-01 2.7692298496088996e-01 
4.8537564872284122e-01 7.9220732955955442e-01 9.3399324775755055e-01 6.5547789017755664e-01 4.6171390631153941e-02 
8.0028046888880011e-01 9.5949242639290300e-01 6.7873515485777347e-01 1.7118668781156177e-01 9.7131781235847536e-02 
Process [0] 
1 
1 
1 
1 
1 
Process [1] 
1 
1 
1 
1 
1 
[0]PETSC ERROR: [1]PETSC ERROR: --------------------- Error Message ------------------------------------ 
[1]PETSC ERROR: Nonconforming object sizes! 
[1]PETSC ERROR: Mat mat,Vec x: global dim 5 10! 
[1]PETSC ERROR: ------------------------------------------------------------------------ 
[1]PETSC ERROR: Petsc Release Version 3.1.0, Patch 5, Mon Sep 27 11:51:54 CDT 2010 
[1]PETSC ERROR: See docs/changes/index.html for recent updates. 
[1]PETSC ERROR: See docs/faq.html for hints about trouble shooting. 
[1]PETSC ERROR: --------------------- Error Message ------------------------------------ 
[0]PETSC ERROR: Nonconforming object sizes! 
[0]PETSC ERROR: Mat mat,Vec x: global dim 5 10! 
[0]PETSC ERROR: See docs/index.html for manual pages. 
[1]PETSC ERROR: ------------------------------------------------------------------------ 
[1]PETSC ERROR: ./ex4 on a linux-gnu named gaurish108-laptop by gaurish108 Mon Jan 17 23:49:18 2011 
[1]PETSC ERROR: Libraries linked from /home/gaurish108/Desktop/ResearchMeetings/SUPERPETS/petsc-3.1-p5/linux-gnu-c-debug/lib 
[1]PETSC ERROR: Configure run at Sat Nov 13 20:34:38 2010 
[1]PETSC ERROR: Configure options --with-cc=gcc --with-fc=gfortran --download-f-blas-lapack=1 --download-mpich=1 --download-superlu_dist=1 --download-parmetis=1 --with-superlu_dist=1 --with-parmetis=1 
[1]PETSC ERROR: ------------------------------------------------------------------------ 
[1]PETSC ERROR: MatMultTranspose() line 1947 in src/mat/interface/matrix.c 
[1]PETSC ERROR: KSPSolve_CGNE() line 103 in src/ksp/ksp/impls/cg/cgne/cgne.c 
[1]PETSC ERROR: KSPSolve() line 396 in src/ksp/ksp/interface/itfunc.c 
[1]PETSC ERROR: main() line 78 in src/mat/examples/tutorials/ex4.c 
application called MPI_Abort(MPI_COMM_WORLD, 60) - process 1[cli_1]: aborting job: 
application called MPI_Abort(MPI_COMM_WORLD, 60) - process 1 
[0]0:Return code = 0, signaled with Interrupt 
[0]1:Return code = 60 
gaurish108 at gaurish108-laptop:~/Desktop$ 


















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