On Aug 31, 2010, at 1:03 PM, Jeremy Roberts wrote: > > Hi Barry, > > Thanks for the quick response. > > I have the unknown vector u globally accessible and so forgo use of the > user-defined context (I tried to get it to work---can it be used in Fortran?). > > I used > > call SNESSetJacobian( snes, Jshell, Jshell, FOO, PETSC_NULL_OBJECT, ierr ) > > where FOO is an empty function having the correct argument types. It seems > to work now, and I get the exact same answer using an explicit Jacobian > matrix and the shell version. Is there a way to get around needing FOO at > all? >
If it works great. But I how you know what the "unknown vector u " that is "globally accessible" in SNES is? How do you know it is the same each time a new Jacobian is needed? The only save way is to copy the vector passed into the FOO funcion. Barry > Jeremy > >
