Hi,
My question concerns repeated solving a nonlinear system for multiple times. I
am trying
to fit some input parameters for an inherently unstable nonlinear implicit
system. Fewer
than 5 parameters need fitting, so it is a small parameter-fitting problem. To
fulfill
this goal, I am solving the nonlinear system repeatedly as follows:
NonlinearImplicitSystem system;
Initialize the input parameters to the object "system";
Repeat
Update the input parameters to "system"; (The update does NOT depend on
the system's
current solution.)
system.solve();
Until system.solution() meets the defined goal
Here is my problem: because the system is by nature unstable, system.solve()
sometimes did
not converge; then in the next round of solve, I obtained a very odd solution
even though
system.solve() converged well. My question is whether a failed nonlinear solve
will leave
some bad intermediate values in the NonlinearSystem object and thereby
influence its next
solve? For example, I think that the system.solution will be used as the
initial guess in
the next solve; then will a partial solution be bad enough to crash the system?
In my problem, the input parameters were updated independently from
system.solution. Also
my update change was small, thus unlikely responsible for the failure of the
next solve.
The remaining uncertainty is the NonlinearSystem's partial solution or its
internal state
variables.
Any comments will be greatly appreciated.
Best,
Dafang
--
Dafang Wang, Ph.D.
Postdoctoral Fellow
Institute of Computational Medicine
Hackerman Hall, Room 218
Johns Hopkins University, Baltimore, 21218
http://lagniappe.icm.jhu.edu/~dwang/
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