55 PetscReal u_exact(PetscReal x, PetscReal y)  in u_exact()  function
73   Vec           u, u_exact;  in main()  local
106   PetscCall(VecDuplicate(u, &u_exact));  in main()
107   PetscCall(FormExactSolution(&info, u_exact));  in main()
108   PetscCall(VecAXPY(u, -1.0, u_exact)); /* u <-- u - u_exact */  in main()
113   PetscCall(VecDestroy(&u_exact));  in main()
133       au[j][i] = u_exact(x, y);  in FormExactSolution()
178         af[j][i] = 4.0 * (au[j][i] - u_exact(x, y));  in FormFunctionLocal()
180         uw       = (i - 1 == 0) ? u_exact(x - dx, y) : au[j][i - 1];  in FormFunctionLocal()
181         ue       = (i + 1 == info->mx - 1) ? u_exact(x + dx, y) : au[j][i + 1];  in FormFunctionLocal()
182         us       = (j - 1 == 0) ? u_exact(x, y - dy) : au[j - 1][i];  in FormFunctionLocal()
183         un       = (j + 1 == info->my - 1) ? u_exact(x, y + dy) : au[j + 1][i];  in FormFunctionLocal()