Feng Shi <[email protected]> writes: > Hi all, > > For 2-D finite difference problems with dof>1,to use > MatSetValuesBlocked, what should be the indices used in that routine? > Am I right if I just use the indices just like dof=1, but set > (5*dof^2) values at one time?
That is the number of entries in a block row when using a 5-point stencil. The row and column indices are by block, not by scalar. > Specifically, I'm trying to use implicit TS solver with dof>1, as in example > src/ts/examples/tutorials/ex10. I understand for 1-D finite diffrence cases, > we have (3 by dof^2) matrix elements, and we can use as in the example: > MatSetValuesBlocked(B,1,&i,3,col,&K[0][0],INSERT_VALUES); > to insert/form the Jacobian. In my 2-D cases with dof=3, I use 5-point finite > difference regime, which means I will have (5*3^2=45) elements Jacobian to be > set at one time as in the example, right? If I use the statement "Matstencil > row, col[5]" as indices to insert values, after we set: "row.i=i, row.j=j and > col[1:5].i=..., col[1:5].j=...", then just simply use: > MatSetValuesBlocked(B,1,&row, 5, &col, &K[0][0],INSERT_VALUES); > to insert these (5*3^2) values to form the Jacobian? > > I'm also confused by the dof defined in the Mat. Does it mean for each node, > there are (dof^2) elements? What "dof defined in the Mat"?
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