From: Stefano Zampini Date: Tue, 17 Jan 2023 07:06:55 +0000 (+0300) Subject: Add comments X-Git-Tag: v9.5.0-rc1~634^2 X-Git-Url: https://gitweb.dealii.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=refs%2Fpull%2F14683%2Fhead;p=dealii.git Add comments --- diff --git a/source/lac/petsc_parallel_sparse_matrix.cc b/source/lac/petsc_parallel_sparse_matrix.cc index 754f827af6..1d1e04efee 100644 --- a/source/lac/petsc_parallel_sparse_matrix.cc +++ b/source/lac/petsc_parallel_sparse_matrix.cc @@ -230,6 +230,9 @@ namespace PETScWrappers sparsity_pattern.n_cols()); AssertThrow(ierr == 0, ExcPETScError(ierr)); + // Use MATAIJ which dispatches to SEQAIJ + // if the size of the communicator is 1, + // and to MPIAIJ otherwise. ierr = MatSetType(matrix, MATAIJ); AssertThrow(ierr == 0, ExcPETScError(ierr)); @@ -293,9 +296,13 @@ namespace PETScWrappers } - // then call the petsc function + // then call the petsc functions // that summarily allocates these - // entries: + // entries. + // Here we both call the specific API since this is how + // PETSc polymorphism works. If the matrix is of type MPIAIJ, + // the second call is dummy. If the matrix is of type SEQAIJ, + // the first call is dummy. ierr = MatMPIAIJSetPreallocationCSR(matrix, rowstart_in_window.data(), colnums_in_window.data(), @@ -365,6 +372,9 @@ namespace PETScWrappers sparsity_pattern.n_cols()); AssertThrow(ierr == 0, ExcPETScError(ierr)); + // Use MATAIJ which dispatches to SEQAIJ + // if the size of the communicator is 1, + // and to MPIAIJ otherwise. ierr = MatSetType(matrix, MATAIJ); AssertThrow(ierr == 0, ExcPETScError(ierr)); @@ -425,7 +435,11 @@ namespace PETScWrappers // then call the petsc function // that summarily allocates these - // entries: + // entries. + // Here we both call the specific API since this is how + // PETSc polymorphism works. If the matrix is of type MPIAIJ, + // the second call is dummy. If the matrix is of type SEQAIJ, + // the first call is dummy. ierr = MatSeqAIJSetPreallocationCSR(matrix, rowstart_in_window.data(), colnums_in_window.data(),