Event trigger


Trigger is a property of an Event object

A Trigger is a condition that must become true for an event to execute. You can use a combination of relational and logical operators to build a trigger expression. Trigger can be a string, an expression, or a function handle that when evaluated returns a value of true or false. A Trigger can access species, parameters, and compartments.

A trigger can contain the keyword time and relational operators to trigger an event that occurs at a specific time during the simulation. For example, time >= x. In this example trigger, note that:

  • The units associated with the keyword time are the units for the TimeUnits property for the Configset object associated with the simulation.

  • If x is an expression containing compartments, species, or parameters, then any units associated with the expression must have the same dimensions as the keyword time.

  • If x is a raw number, then its dimensions (and units, if unit conversion is on) are assumed to be the same as the keyword time.

For more information about how the SimBiology® software handles events, see How Events Are Evaluated. For examples of event functions, see Specifying Event Triggers.


Applies toObject: event
SimBiology typeString, function handle
SimBiology values

Specify a MATLAB® expression as a string. Default is '' (empty string).



  1. Create a model object, and then add an event object.

    modelObj = sbmlimport('oscillator');
    eventObj = addevent(modelObj, 'time>= 5', 'OpC = 200');
  2. Set the Trigger property of the event object.

    set(eventObj, 'Trigger', '(time >=5) && (speciesA<1000)');
  3. Get the Trigger property.

    get(eventObj, 'Trigger')
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