# Control algorithm terminationΒΆ

In this examples we are going to expose ways to control the termination of optimization and simulation algorithms using callbacks.

```import openturns as ot

ot.Log.Show(ot.Log.NONE)
```

Define an event to compute a probability

```myFunction = ot.SymbolicFunction(["E", "F", "L", "I"], ["-F*L^3/(3.0*E*I)"])
dim = myFunction.getInputDimension()
mean = [50.0, 1.0, 10.0, 5.0]
sigma = [1.0] * dim
R = ot.IdentityMatrix(dim)
myDistribution = ot.Normal(mean, sigma, R)
vect = ot.RandomVector(myDistribution)
output = ot.CompositeRandomVector(myFunction, vect)
myEvent = ot.ThresholdEvent(output, ot.Less(), -3.0)
```

Stop a FORM algorithm using a calls number limit

A FORM algorithm termination can be controlled by the maximum number of iterations

of its underlying optimization solver, but not directly by a maximum number of evaluations.

Create the optimization algorithm

```myCobyla = ot.Cobyla()
myCobyla.setMaximumCallsNumber(400)
myCobyla.setMaximumAbsoluteError(1.0e-10)
myCobyla.setMaximumRelativeError(1.0e-10)
myCobyla.setMaximumResidualError(1.0e-10)
myCobyla.setMaximumConstraintError(1.0e-10)
```

Define the stopping criterion

```def stop():
return myFunction.getCallsNumber() > 100

myCobyla.setStopCallback(stop)
```

Run FORM

```myAlgo = ot.FORM(myCobyla, myEvent, mean)
myAlgo.run()
result = myAlgo.getResult()
print("event probability:", result.getEventProbability())
print("calls number:", myFunction.getCallsNumber())
```
```event probability: 0.15642619197777585
calls number: 1
```

Stop a simulation algorithm using a time limit

Here we will create a callback to not exceed a specified simulation time.

Create simulation

```experiment = ot.MonteCarloExperiment()
myAlgo = ot.ProbabilitySimulationAlgorithm(myEvent, experiment)
myAlgo.setMaximumOuterSampling(1000000)
myAlgo.setMaximumCoefficientOfVariation(-1.0)
```

Define the stopping criterion

```myAlgo.setMaximumTimeDuration(0.01)
```

Run algorithm

```myAlgo.run()
result = myAlgo.getResult()
print("event probability:", result.getProbabilityEstimate())
print("calls number:", myFunction.getCallsNumber())
```
```event probability: 0.13995680345572342
calls number: 4631
```