[petsc-users] MatZeroRowsColumns

[Smith, Barry F.]

MatZeroRowsColumns() as two vector arguments you are missing


> On Nov 23, 2017, at 2:43 PM, Samuel Lanthaler <s.lanthaler at gmail.com> wrote:
> 
> Hi there, 
> I'm new to PETSc and have been trying to do some basic manipulation of matrices in fortran, but don't seem to be able to set a row/column to zero using the MatZeroRowsColumns command: The following is a small example program:
> 
> ! initialize PETSc
>   CALL PetscInitialize(PETSC_NULL_CHARACTER,ierr)
> 
>   ! Set up a new matrix
>   m = 3
>   CALL MatCreate(PETSC_COMM_WORLD,matA,ierr); CHKERRQ(ierr);
>   CALL MatSetType(matA,MATMPIAIJ,ierr); CHKERRQ(ierr);
>   CALL MatSetSizes(matA,PETSC_DECIDE,PETSC_DECIDE,m,m,ierr); CHKERRQ(ierr);
>   CALL MatMPIAIJSetPreallocation(matA,3,PETSC_NULL_INTEGER,3,PETSC_NULL_INTEGER,ierr); CHKERRQ(ierr);
> 
>   ! set values of matrix
>   vals(1,:) = (/1.,2.,3./)
>   vals(2,:) = (/4.,5.,6./)
>   vals(3,:) = (/7.,8.,9./)
>   ! 
>   idxm = (/0,1,2/)
>   idxn = (/0,1,2/)
>   !
>   CALL MatSetValues(matA,3,idxm,3,idxn,vals,INSERT_VALUES,ierr); CHKERRQ(ierr);
>   
>   ! assemble matrix
>   CALL MatAssemblyBegin(matA,MAT_FINAL_ASSEMBLY,ierr); CHKERRQ(ierr);
>   CALL MatAssemblyEnd(matA,MAT_FINAL_ASSEMBLY,ierr); CHKERRQ(ierr);
>  
>   ! set one row/column to zero, put 6.0d0 on diagonal
>   idone(1) = 2
>   val = 6.0d0
>   CALL MatZeroRowsColumns(matA,1,idone,val,ierr); CHKERRQ(ierr);
> 
> ! finalize PETSc
>   CALL PetscFinalize(PETSC_NULL_CHARACTER,ierr)
> 
> When running the program, I get the following error message:
> 
> [0]PETSC ERROR: ------------------------------------------------------------------------
> [0]PETSC ERROR: Caught signal number 11 SEGV: Segmentation Violation, probably memory access out of range
> [0]PETSC ERROR: Try option -start_in_debugger or -on_error_attach_debugger
> [0]PETSC ERROR: or see http://www.mcs.anl.gov/petsc/documentation/faq.html#valgrind
> [0]PETSC ERROR: or try http://valgrind.org on GNU/linux and Apple Mac OS X to find memory corruption errors
> [0]PETSC ERROR: likely location of problem given in stack below
> [0]PETSC ERROR: ---------------------  Stack Frames ------------------------------------
> [0]PETSC ERROR: Note: The EXACT line numbers in the stack are not available,
> [0]PETSC ERROR:       INSTEAD the line number of the start of the function
> [0]PETSC ERROR:       is given.
> [0]PETSC ERROR: --------------------- Error Message --------------------------------------------------------------
> [0]PETSC ERROR: Signal received
> [0]PETSC ERROR: See http://www.mcs.anl.gov/petsc/documentation/faq.html for trouble shooting.
> [0]PETSC ERROR: Petsc Release Version 3.8.2, Nov, 09, 2017 
> [0]PETSC ERROR: ./test on a arch-complex-debug named sam-ThinkPad-T450s by sam Thu Nov 23 23:28:15 2017
> [0]PETSC ERROR: Configure options PETSC_DIR=/home/sam/Progs/petsc-3.8.2 PETSC_ARCH=arch-complex-debug --with-scalar-type=complex
> [0]PETSC ERROR: #1 User provided function() line 0 in  unknown file
> --------------------------------------------------------------------------
> MPI_ABORT was invoked on rank 0 in communicator MPI_COMM_WORLD 
> with errorcode 59.
> Would someone be so kind as to tell me what I'm doing wrong? Thank you!
> 
> Best regards,
> Sam