> We have intention to use CVODE's multi-time-step control, and use Petsc > solving linear and non-linear systems at each time step. > Is this what you need? Yes, that is exactly what I mean. > Current interface uses SUNDAILS solvers. > > The interface is implemented in > ~petsc/src/ts/impls/implicit/sundials/sundials.c Thanks, I will look into that. Jianing