CommonProblems

Unable to meet integration tolerances…​ error

One of the most common errors that occurs with the PDEPE is the following error:

Warning: Failure at t=4.060671e-03.
Unable to meet integration tolerances without reducing the step size below the smallest value allowed (1.387779e-17) at time t.

This is a general error that can occur due to incorrect boundary conditions, non-physical transport equations, bad initial conditions etc.

If the simulation without modification then the most common cause for this error is a time step (i.e. the value of tmax) that is too large. Try breaking the solution down into smaller parts with a very short initial time step. An example of this can be found at the end of equilibrate function where two solutions are used to reach equilibrium with mobile ions.

It is important to remember when writing procedures to change the initial time value t0 in addition to tmax.