[petsc-users] Insert values into matrix using MatSetValuesStencil

[Timothée Nicolas]

The first thing that strikes me is your definition of the stencils

*MatStencil  :: row(6,1),col(6,7)*

Why is it not defined with

*MatStencil  :: row(4,1),col(4,7)*

instead ?

Where does the 6 come from ?

Timothée


2015-09-23 17:14 GMT+09:00 TAY wee-beng <zonexo at gmail.com>:

> Hi,
>
> I have successfully used MatSetValuesStencil to insert values into a
> Poisson eqn matrix which has 1 DOF (pressure). Now I'm trying to insert
> values in a momentum eqn matrix which has 3 DOF (u,v,w)
>
> However, I got the error:
>
> *[0]PETSC ERROR: --------------------- Error Message
> ----------------------------*
> *----------------------------------*
> *[0]PETSC ERROR: Argument out of range*
> *[0]PETSC ERROR: Inserting a new nonzero at (111,5) in the matrix*
> *[0]PETSC ERROR: See http://www.mcs.anl.gov/petsc/documentation/faq.html
> <http://www.mcs.anl.gov/petsc/documentation/faq.html> for trou*
> *ble shooting.*
>
> I wonder what's wrong.  For the momentum eqn, for each DOF, at at node
> (dof,i,j,k), I have coupling i +/- 1, j +/- 1 and k +/- 1.
>
> The error happens at 111,5, which corresponds to i = 2, j = 2, k = 2,
> which is an internal node.
>
> Here's part of my code below. Hope someone can help. Thanks!
>
> *PetscScalar :: value_insert(7)*
>
> *MatStencil  :: row(6,1),col(6,7)*
>
> *ione = 1;   iseven = 7*
>
> *if (cell_type == 'u') then*
>
> *    offset = 1*
>
> *else if (cell_type == 'v') then*
>
> *    offset = 2*
>
> *else if (cell_type == 'w') then*
>
> *    offset = 3*
>
> *end if*
>
> *do k=ksta2,kend2*
>
> *    do j = jsta2,jend2*
>
> *        do i=2,size_x-1*
>
> *            row(MatStencil_i,1) = i - 1*
>
> *            row(MatStencil_j,1) = j - 1*
>
> *            row(MatStencil_k,1) = k - 1*
>
> *            row(MatStencil_c,1) = offset - 1*
>
> *            value_insert = 0.d0*
>
> *            col(MatStencil_i,3) = i + 1 - 1 !east*
>
> *            col(MatStencil_j,3) = j - 1*
>
> *            col(MatStencil_k,3) = k - 1*
>
> *            col(MatStencil_c,3) = offset - 1*
>
> *            value_insert(3) = -(
> 1./(cell_x(i)%pd_E+cell_x(i+1)%pd_W))*(c_yz(j,k)%fc_E)*inv_Re*
>
> *            col(MatStencil_i,5) = i - 1 - 1 !west*
>
> *            col(MatStencil_j,5) = j - 1*
>
> *            col(MatStencil_k,5) = k - 1*
>
> *            col(MatStencil_c,5) = offset - 1*
>
> *            value_insert(5) = -(
> 1./(cell_x(i)%pd_W+cell_x(i-1)%pd_E))*(c_yz(j,k)%fc_E)*inv_Re*
>
> *            col(MatStencil_i,2) = i - 1 !north*
>
> *            col(MatStencil_j,2) = j + 1 - 1*
>
> *            col(MatStencil_k,2) = k - 1*
>
> *            col(MatStencil_c,2) = offset - 1*
>
> *            value_insert(2) = -(
> 1./(cell_y(j)%pd_N+cell_y(j+1)%pd_S))*(c_zx(i,k)%fc_N)*inv_Re*
>
> *            col(MatStencil_i,4) = i - 1 !south*
>
> *            col(MatStencil_j,4) = j - 1 - 1*
>
> *            col(MatStencil_k,4) = k - 1*
>
> *            col(MatStencil_c,4) = offset - 1*
>
> *            value_insert(4) = -(
> 1./(cell_y(j)%pd_S+cell_y(j-1)%pd_N))*(c_zx(i,k)%fc_N)*inv_Re*
>
> *            col(MatStencil_i,6) = i - 1 !front*
>
> *            col(MatStencil_j,6) = j - 1*
>
> *            col(MatStencil_k,6) = k + 1 - 1*
>
> *            col(MatStencil_c,6) = offset - 1*
>
> *            value_insert(6) = -(
> 1./(cell_z(k)%pd_F+cell_z(k+1)%pd_B))*(c_xy(i,j)%fc_F)*inv_Re*
>
> *            col(MatStencil_i,7) = i - 1 !back*
>
> *            col(MatStencil_j,7) = j - 1*
>
> *            col(MatStencil_k,7) = k - 1 - 1*
>
> *            col(MatStencil_c,7) = offset - 1*
>
> *            value_insert(7) = -(
> 1./(cell_z(k)%pd_B+cell_z(k-1)%pd_F))*(c_xy(i,j)%fc_F)*inv_Re*
>
> *            col(MatStencil_i,1) = i - 1*
>
> *            col(MatStencil_j,1) = j - 1*
>
> *            col(MatStencil_k,1) = k - 1*
>
> *            col(MatStencil_c,1) = offset - 1*
>
> *            value_insert(1) = 2.*c(i,j,k)%vol/del_t -
> (value_insert(2)+value_insert(3)+value_insert(4)+value_insert(5)+value_insert(6)+value_insert(7))*
>
> *            call
> MatSetValuesStencil(A_semi_xyz,ione,row,iseven,col,value_insert,INSERT_VALUES,ierr)*
>
> *        end do*
>
> *    end do*
>
> *end do    *
>
> Thank you
>
> Yours sincerely,
>
> TAY wee-beng
>
>
>
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