[petsc-users] MAT_REUSE_MATRIX

[irfan.khan at gatech.edu]

I get the following error at the call for MatMatMult(Mat A,Mat B,MatReuse scall, PetscReal fill,Mat *C).

Error: Container does not exit! 

Is the probable cause of this error an invalid C matrix?. Can I use MAT_REUSE_MATRIX in MatMatMult() and use an existing C matrix. The call works fine when I use MAT_INITIAL_MATRIX and use a new matrix.

Here are the sequence of steps.

       /* Generating A & B matrices by copying the global stiffness matrix */
        ierr = MatConvert(global->Amat, MATSAME, MAT_INITIAL_MATRIX, &A);CHKERRQ(ierr);
        ierr = MatConvert(global->Amat, MATSAME, MAT_INITIAL_MATRIX, &B);CHKERRQ(ierr);

        /* Zero all the entries of the A matrix */
        ierr = MatZeroEntries(A);CHKERRQ(ierr);

        /* Fill in the diagonal entry and one off-diagonal entry of A matrix */
        for(i = 0; i < bc.numPeriodic; i++){
                if(bc.periodNode[i] > -1){
                        for(j = 0; j < dofn; j++){
                                row = local2Petsc[bc.periodNode[i]*dofn+j];
                                col = bc.periodPair[i]*dofn+j;
                        /* The diagonal Entry */
                                ierr =MatSetValue(A,row,row,1.0,ADD_VALUES);CHKERRQ(ierr);
                        /* The entry for periodic node */
                                ierr =MatSetValue(A,row,col,1.0,ADD_VALUES);CHKERRQ(ierr);
                        }
                }
        }

        /* Assemble the new matrices */
        ierr = MatAssemblyBegin(A, MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);
        ierr = MatAssemblyEnd(A, MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);
        ierr = MatAssemblyBegin(B, MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);
        ierr = MatAssemblyEnd(B, MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);

        /* Perform matrix multiplication of A and B(Amat) to add rows of periodic
         * nodes. Save the new matrix in Amat */
        ierr = MatMatMult(A,B,MAT_REUSE_MATRIX,PETSC_DEFAULT,&global->Amat);CHKERRQ(ierr);

        ierr = MatDestroy(A);CHKERRQ(ierr);
        ierr = MatDestroy(B);CHKERRQ(ierr);


Thank you
Irfan

----- Original Message ----- 
From: "Matthew Knepley" <knepley at gmail.com> 
To: "PETSc users list" <petsc-users at mcs.anl.gov> 
Sent: Monday, May 10, 2010 12:26:14 PM GMT -05:00 US/Canada Eastern 
Subject: Re: [petsc-users] MAT_REUSE_MATRIX 

On Mon, May 10, 2010 at 12:07 PM, < irfan.khan at gatech.edu > wrote: 



Hi Petsc Team, 

When using the subroutine MatMatMult(Mat A,Mat B,PetscReal fill,Mat *C) with option MAT_REUSE_MATRIX, Can the C matrix be any one of A or B? 



I do not think that is safe. I believe C needs to be another matrix, but it can be 
reused for successive multiplies. 


Matt 


Thank you 
Irfan 

----- Original Message ----- 
From: "Matthew Knepley" < knepley at gmail.com > 
To: "PETSc users list" < petsc-users at mcs.anl.gov > 
Sent: Friday, May 7, 2010 4:03:42 PM GMT -05:00 US/Canada Eastern 
Subject: Re: [petsc-users] Adding MatAij rows 

On Fri, May 7, 2010 at 3:57 PM, < irfan.khan at gatech.edu > wrote: 






Petsc Team, 

Is there a function that can be used to add two rows and put the results into a third row of the same parallel matrix (MPIAIJ)? i.e 

A[k][l] = A[i][l] + A[j][l] 



No, since it would entail messing with the nonzero structure. You could easily 
use a second matrix to get this effect from subsequent MatMult() calls. 


Matt 





Thank you 
Irfan 

-- 
PhD Candidate 
G.W. Woodruff School of Mechanical Engineering 
Georgia Institute of Technology 
Atlanta, GA (30332) 



-- 
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 


-- 
PhD Candidate 
G.W. Woodruff School of Mechanical Engineering 
Georgia Institute of Technology 
Atlanta, GA (30332) 



-- 
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 


-- 
PhD Candidate 
G.W. Woodruff School of Mechanical Engineering 
Georgia Institute of Technology 
Atlanta, GA (30332)