Hello I'm using the petsc-dev TS system to solve a system
u' = F(u) and would like to supply my own preconditioner to the KSP linear solver inside the SNES nonlinear solver. The Jacobian of the system is difficult to evaluate, so I would like to remain matrix-free. I have however got an approximate inverse operator of the linear system being solved by KSP: (I - alpha*J) In SUNDIALS it's possible to supply a preconditioner function which is then called passing the system state, vector to be preconditioned, and the alpha parameter. To do this in PETSc, should I define a MatShell or PCShell, and is there a way to get alpha from the TS? Thanks in advance Ben Dudson Department of Physics University of York
