Good morning, I am currently having some trouble in the creation of some matrices.
I am using structured dmda objects to create matrices using the DMCreate() function. One of these matrices will be the result of a matrix-matrix product of two of these dm matrices. I know that the matrix product will have more nonzero entries or at least a bigger stencil than the original dm matrices, however I accounted for that when I set the DMDA stencil width in the initial creation. The problem is that even with that, the resulting matrix-matrix product has a bigger stencil as evidenced by failure in subsequent matrix copy/addition operations using SAME_NONZERO_PATTERN. Judging by the difference of the nonzero entries I believe that initial zero entries (the ones I initialized to eventually hold this expaned stencil) on the original dm matrices are being combined to further expand the stencil of the product matrix. Is there any way of getting a matrix-matrix product that will keep the same nonzero pattern as the dm matrices? I have tried both MatMatMult() and the MatProductCreate() sequence so far, but both produce nonzero patterns that do not match the dm nonzero pattern. Thank you, -Alfredo -- Alfredo Duarte Graduate Research Assistant The University of Texas at Austin