On Tue, 31 Aug 2010 14:17:00 -0400, Jeremy Roberts <j.alyn.roberts at gmail.com> wrote: > To implement the safe method---i.e. copying the unknown vector u within > FOO---what is proper generic form of FOO? > > I guess I'm not clear exactly how FOO and jac_shell (the J*x routine) are > linked. It appears they aren't, given I can use an empty subroutine, but > how then is a local copy of u within FOO used in for J(u) in J(U)*x of > jac_shell?
FOO is the function called to *update* the Jacobian. It has the same prototype as the FormJacobian routines you see in the examples: FormJacobian(snes,X,J,Jpre,matstructure,user,ierr) It sounds like you just need to save the vector. Jed
