171     Mat matB;  in main()  local
173     PetscCall(MatCreate(PETSC_COMM_WORLD, &matB));  in main()
174     PetscCall(MatSetSizes(matB, PETSC_DECIDE, PETSC_DECIDE, m, n));  in main()
175     PetscCall(MatSetFromOptions(matB));  in main()
176     PetscCall(MatSetUp(matB));  in main()
177     PetscCall(MatGetOwnershipRange(matB, &rstart, &rend));  in main()
182         PetscCall(MatSetValues(matB, 1, &i, 1, &j, &v, INSERT_VALUES));  in main()
185     PetscCall(MatAssemblyBegin(matB, MAT_FINAL_ASSEMBLY));  in main()
186     PetscCall(MatAssemblyEnd(matB, MAT_FINAL_ASSEMBLY));  in main()
190     PetscCall(MatView(matB, PETSC_VIEWER_STDOUT_WORLD));  in main()
192     PetscCall(MatAXPY(mat, alpha, matB, SUBSET_NONZERO_PATTERN));  in main()
194     PetscCall(MatDestroy(&matB));  in main()