[petsc-users] Optional arguments of MatZeroRows

[Karl Rupp]

> It seems that
> /MatZeroRows(mat,numRows,rows,diag,*NULL*,*NULL*)/
> also works.
>
> Is it better to pass NULL instead of 0?

both should be fine, unless you use an ancient compiler which does not 
define NULL...

Best regards,
Karli


> ------------------------------------------------------------------------
>
>     *De: *"Cedric Doucet" <cedric.doucet at inria.fr>
>     *À: *petsc-users at mcs.anl.gov
>     *Envoyé: *Mercredi 13 Août 2014 10:09:40
>     *Objet: *[petsc-users] Optional arguments of MatZeroRows
>
>     Hello,
>
>     I want to use MatZeroRows function
>     (http://www.mcs.anl.gov/petsc/petsc-current/docs/manualpages/Mat/MatZeroRows.html).
>
>     It is said in the documentation that the last two arguments are
>     optional, i.e. x and b vectors:
>     /PetscErrorCode MatZeroRows(Mat mat,PetscInt numRows,const PetscInt
>     rows[],PetscScalar diag,*Vec x*,*Vec*/*b*)
>     However, a call to
>     /MatZeroRows(mat,numRows,rows,diag)/
>     does not seem to work because the last two input arguments are required.
>
>     In examples, e.g. src/ksp/ksp/examples/tutorials/ex3.c.html
>     <http://www.mcs.anl.gov/petsc/petsc-current/src/ksp/ksp/examples/tutorials/ex3.c.html>,
>     it seems that optional arguments are passed by putting some zero
>     values instead of vectors:
>     /MatZeroRows(mat,numRows,rows,diag,*0*,*0*)/
>
>     Is this the right way to use MatZeroRows function when one does not
>     want to pass x and b vectors as input arguments?
>
>     Best,
>
>     Cédric
>
>
>