Unable to meet integration tolerances without reducing the step size below the smallest value allowed (3.552714e-15) at time t.

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MarionJ
MarionJ 2017-5-12
编辑： Torsten 2023-3-30
Hello
Using the parabolic-solver to solve thermal conduction equation I got following message: Warning: Failure at t=1.127658e+00. Unable to meet integration tolerances without reducing the step size below the smallest value allowed (3.552714e-15) at time t. The failure occurs in ode15s-solver.
I have absolutely no idea where to start failure search... and I am very grateful for any help.
LF

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Star Strider
Star Strider 2017-5-12
That error usually occurs when your function creates a singularity or other discontinuity (with an Inf or NaN result) at the specified time. The only way to determine that is to examine the output of your ode15s call to see what the values are when it stops.
Plotting the output (all columns of the result as functions of your independent variable) will probably tell you everything you need to know about the problem.
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Amanda Gregory
Amanda Gregory 2023-3-30
Also experiencing this issue. My understanding was the PDE solver serched for NaN values to determine nonlinearity, is this not the case?
Torsten
Torsten 2023-3-30
编辑：Torsten 2023-3-30
is this not the case?
No. Detecting NaN values during a computation will make the solver stop immediately. This applies at least for the underlying ODE integrator (ode15s). I don't know about possible functionalities of the superordinate PDE solver.

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