I'm currently getting very long propagation times when attempting to use the Time Stepping propagators in Petsc 3.2, and in the interest of speeding things up, I'm curious how I can reduce the accuracy (or see what it is in the first place) to speed it up.
nonlinear systems of equations
In general, the
PETSc TS propagators solve a nonlinear system of equations at each time step, so you would need to access the
SNES object and modify its accuracy tolerance there. See the documentation on
SNESSetFromOptions for a list of the command line options available to you for adjusting the solver tolerances.
linear system of equations
PETSc doesn't expose the
KSP object belonging to
TS in the same way at the command-line, @JedBrown or @MattKnepley may be able to comment on why. Programmatically, you can: