ode events tutorial

Locate events during ODE integration.

📄Description

Use the Events option to stop or record integration points where an event function crosses zero. Event functions return value, terminal, and direction arrays.

Event output	Meaning
te or xe	Time or independent variable value where an event was located.
ye	Solution at the event point.
ie	Index of the event function that crossed zero.
isterminal	Nonzero values stop integration at the event.

Use terminal events to stop at thresholds and nonterminal events to collect diagnostic times without stopping the integration.

💡Examples

Stop when the state reaches one half.

function [value,isterminal,direction] = localHalfEvent(t, y)
  value = y - 0.5;
  isterminal = 1;
  direction = 1;
end
options = odeset('Events', @localHalfEvent);
[t, y, te, ye, ie] = ode45(@(t,y) 1, [0 1], 0, options)

Use an event object in the object workflow.

event = odeEvent('EventFcn', @(t,y) y - 0.5, 'Response', 'stop');
problem = ode('ODEFcn', @(t,y) 1, 'InitialValue', 0, 'EventDefinition', event);
result = solve(problem, 0, 1)

🔗See Also

odeset odeEvent ode45

🕔Version History

Version	Description
2.0.0	initial version

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