Matrix C should always inherit the number of local rows from A and the number of local columns from B. Is it not the case for your code? If so, please provide a MWE to reproduce Also, which version of PETSc are you using?
Il Dom 19 Apr 2020, 19:21 Marius Buerkle <mbuer...@web.de> ha scritto: > > Hi, > > I have a question about the behavior of MAT_INITIAL_MATRIX for MatMatMult. > I a have a set of MPIDENSE and MPIAIJ matrices for which I have defined the > number of local rows (and local columns) manually, i.e. not used > PETSC_DECIDE for MatSetSizes. The number of local rows is different from > what PETSC_DECIDE would choose. If I do a MatMatMult with A=MPIDENSE and > B=MPIAIJ with MAT_INITIAL_MATRIX then matrix C will have the number of > local rows corresponding to A and B, namely what I have defined with > MatSetSizes when creating the matrices A and B. But when both matrices are > dense, A=MPIDENSE and B=MPIDENSE, then the resulting matrix C will have > different number of local rows, namely what I would get with if I would > create the matrix with PETSC_DECIDE. Is this behavior normal? The problem > is that I have to multiply both resulting matrices which will then throw a > "Nonconforming object sizes error" as they have different number of local > rows. Any ideas what goes wrong here? > > > Marius >
