[petsc-users] Optional arguments of MatZeroRows

[Cedric Doucet]

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 , 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 


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