Main Content


Set or clear breakpoint to pause when Inf or NaN value occurs in simulation debugging session



nanbreak sets or clears a breakpoint that pauses simulation when a NaN or Inf value occurs in the model during a simulation debugging session.

  • If the breakpoint was not set, the command sets the breakpoint.

  • If the breakpoint had been set, the command clears the breakpoint.

The Inf or NaN value breakpoint can help you to locate and investigate computational issues in your model.

You can use this function in a simulation debugging session started:

  • Interactively, using the Simulink® Toolstrip

  • Programmatically, using the sldebug function

  • Programmatically, using the sim function with the 'debug' name-value argument


This function is available only for simulation debugging sessions started programmatically and for interactive simulation debugging sessions while paused within a time step.


To start a simulation debugging session interactively, add one or more breakpoints to your model, and in the Breakpoints List, check that Pause within time step is selected. When the simulation pauses on a breakpoint, some of the programmatic debugging commands, such as the stop command, are available for use in the MATLAB® Command Window.

Version History

Introduced before R2006a

expand all