[petsc-users] Insert values into matrix using MatSetValuesStencil
TAY wee-beng
zonexo at gmail.com
Wed Sep 23 03:37:24 CDT 2015
Hi Timothée,
The matrix is created with 3 dof - u,v,w. So for each i,j,k, there are 3
values. Actually I got 3 eqns from the u,v,w momentum eqns. They are not
coupled together so I can also solve them individually. But I was told
it's faster to group them together. The global indices is something like
this:
i, j, k, ijk global indices, dof
1 1 1 1 u
1 1 1 2 v
1 1 1 3 w
2 1 1 4 u
...
Hope it's clearer now.
Ok, I changed the stencil, it's now working.
Thank you
Yours sincerely,
TAY wee-beng
On 23/9/2015 4:22 PM, Timothée Nicolas wrote:
> Can you also tell how you created the matrix ? Just in case you
> created it with the 1 dof DMDA, it would not work if you try to input
> values at places where it is not allocated (which could explain the
> error message)
>
> 2015-09-23 17:18 GMT+09:00 Timothée Nicolas
> <timothee.nicolas at gmail.com <mailto:timothee.nicolas at gmail.com>>:
>
> 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
> <mailto: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 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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