[petsc-users] MatZeroRowsColumns

[Samuel Lanthaler]

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
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