13   Mat          A, A11, A12, A21, A22;  in main()  local
69   PetscCall(MatCreate(PETSC_COMM_SELF, &A12));  in main()
70   PetscCall(MatSetSizes(A12, size1, size2, size1, size2));  in main()
71   PetscCall(MatSetType(A12, MATSEQDENSE));  in main()
72   PetscCall(MatSeqDenseSetPreallocation(A12, b + size1 * size));  in main()
73   PetscCall(MatDenseSetLDA(A12, size));  in main()
74   PetscCall(MatAssemblyBegin(A12, MAT_FINAL_ASSEMBLY));  in main()
75   PetscCall(MatAssemblyEnd(A12, MAT_FINAL_ASSEMBLY));  in main()
104   PetscCall(MatMultAdd(A12, X2, Z1, Z1));  in main()
119   PetscCall(MatSetValues(A12, 1, &i, 1, &j, &v, INSERT_VALUES));  in main()
127   PetscCall(MatAssemblyBegin(A12, MAT_FINAL_ASSEMBLY));  in main()
128   PetscCall(MatAssemblyEnd(A12, MAT_FINAL_ASSEMBLY));  in main()
134   PetscCall(MatMultAdd(A12, X2, Z1, Z1));  in main()
148   PetscCall(MatMultTransposeAdd(A12, X1, Z2, Z2));  in main()
159   PetscCall(MatDestroy(&A12));  in main()