ODE integrator goes past specified end of integration range
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Key: MATH-358
URL: https://issues.apache.org/jira/browse/MATH-358
Project: Commons Math
Issue Type: Bug
Affects Versions: 2.0
Environment: Linux
Reporter: Luc Maisonobe
Assignee: Luc Maisonobe
Priority: Critical
Fix For: 2.1
End of integration range in ODE solving is handled as an event.
In some cases, numerical accuracy in events detection leads to error in events
location.
The following test case shows the end event is not handled properly and an
integration that should cover a 60s range in fact covers a 160s range, more
than twice the specified range.
{code}
public void testMissedEvent() throws IntegratorException, DerivativeException
{
final double t0 = 1878250320.0000029;
final double t = 1878250379.9999986;
FirstOrderDifferentialEquations ode = new
FirstOrderDifferentialEquations() {
public int getDimension() {
return 1;
}
public void computeDerivatives(double t, double[] y, double[] yDot)
throws DerivativeException {
yDot[0] = y[0] * 1.0e-6;
}
};
DormandPrince853Integrator integrator = new
DormandPrince853Integrator(0.0, 100.0,
1.0e-10, 1.0e-10);
double[] y = { 1.0 };
integrator.setInitialStepSize(60.0);
double finalT = integrator.integrate(ode, t0, y, t, y);
Assert.assertEquals(t, finalT, 1.0e-6);
}
{code}
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