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Time tolerance


Specify a tolerance factor that controls how closely zero-crossing events must occur to be considered consecutive.

Category: Solver


Default: 10*128*eps

  • Simulink® software defines zero crossings as consecutive if the time between events is less than a particular interval. The following figure depicts a simulation timeline during which Simulink software detects zero crossings ZC1 and ZC2, bracketed at successive time steps t1 and t2.

    Simulink software determines that the zero crossings are consecutive if

    dt < RelTolZC * t2

    where dt is the time between zero crossings and RelTolZC is the Time tolerance.

  • Simulink software counts the number of consecutive zero crossings that it detects. If the count exceeds the value of Number of consecutive zero crossings allowed, Simulink software displays either a warning or error as specified by the Consecutive zero-crossings violation diagnostic (see Consecutive zero-crossings violation).


  • Simulink software resets the counter each time it detects nonconsecutive zero crossings (successive zero crossings that fail to meet the relative tolerance setting); therefore, decreasing the relative tolerance value may afford your model's behavior more time to recover.

  • If your model experiences excessive zero crossings, you can also increase the Number of consecutive zero crossings to increase the threshold at which Simulink software triggers the Consecutive zero-crossings violation diagnostic.


To enable this parameter, set the solver Type to Variable-step and set Zero-crossing control to either Use local settings or Enable all.

Programmatic Use

Parameter: ConsecutiveZCsStepRelTol
Type: character vector
Value: any valid value
Default: '10*128*eps'

Recommended Settings

DebuggingNo impact
TraceabilityNo impact
EfficiencyNo impact
Safety precautionNo impact

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