Hi, In SNES, Petsc can compute Jacobian by: ierr = SNESSetJacobian (snes,J,J,SNESDefaultComputeJacobian,PETSC_NULL);CHKERRQ(ierr); How about TS? I don't want to provide Jacobian function by myself, but I didn't find something like TSDefaultComputeJacobian. Many thanks! Xuan YU xxy113 at psu.edu