Matthew Knepley knepley at
Tue May 27 11:13:12 CDT 2008

On Tue, May 27, 2008 at 10:58 AM, Ben Tay <zonexo at> wrote:
> Hi,
> I read in the manual that I can use either call
> MatSetOption(A_mat_uv,MAT_NO_NEW_NONZERO_LOCATIONS,PETSC_TRUE,ierr) or call
> MatSetOption(A_mat,MAT_SYMMETRIC,PETSC_TRUE,ierr).
> When I use MAT_NO_NEW_NONZERO_LOCATIONS for the matrix formed by my momentum
> eqn, I get the error on my home computer udring compiling:
> :\Myprojects2\imb_airfoil_x2_parallel\mom_disz.f90(356) : Error: This name
> does not have a type, and must have an explicit type.
> call MatSetOption(A_mat_uv,MAT_NO_NEW_NONZERO_LOCATIONS,PETSC_TRUE,ierr)

1) It appears this symbol was not defined for Fortran. This is fixed
in petsc-dev.

> Although this error does not happen when I compile in linux, I can this
> error during run:
> ------------------------------------------------------------------------
> [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
> ERROR: or try on linux or man libgmalloc on Apple to
> find memory corruption errors
> [0]PETSC ERROR: configure using --with-debugging=yes, recompile, link, and
> run
> [0]PETSC ERROR: to get more information on the crash.
> [0]PETSC ERROR: --------------------- Error Message
> ------------------------------------
> [0]PETSC ERROR: Signal received!
> ------------------------------------------------------------------------
> I use KSPRICHARDSON and PCILU for my momentum eqn matrix.
> When I use MatSetOption(A_mat,MAT_SYMMETRIC,PETSC_TRUE,ierr) for my poisson
> eqn which is symmetric, I get the same error as above during run. Btw, I'm
> using hypre as the preconditioner and default solver.

This option does not actually do anything. The SEGV must come from
another error.


> May I know why using these options give the error?
> Thank you very much.
> Regards.

What most experimenters take for granted before they begin their
experiments is infinitely more interesting than any results to which
their experiments lead.
-- Norbert Wiener

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