52   Mat               S1, S2;  in main()  local
74   PetscCall(MatCreateShell(PETSC_COMM_WORLD, 2, 2, 2, 2, user, &S1));  in main()
75   PetscCall(MatSetUp(S1));  in main()
76   PetscCall(MatShellSetOperation(S1, MATOP_MULT, (PetscErrorCodeFn *)MatMult_User));  in main()
77   PetscCall(MatShellSetOperation(S1, MATOP_COPY, (PetscErrorCodeFn *)MatCopy_User));  in main()
78   PetscCall(MatShellSetOperation(S1, MATOP_DESTROY, (PetscErrorCodeFn *)MatDestroy_User));  in main()
85   PetscCall(MatScale(S1, 31));  in main()
86   PetscCall(MatShift(S1, 37));  in main()
87   PetscCall(MatDiagonalScale(S1, X, Y));  in main()
88   PetscCall(MatCopy(S1, S2, SAME_NONZERO_PATTERN));  in main()
89   PetscCall(MatMult(S1, X, Y));  in main()
94   PetscCall(MatDestroy(&S1));  in main()