T - the type of the field elementspublic interface RealFieldUnivariateFunction<T extends RealFieldElement<T>>
When a user-defined function encounters an error during
evaluation, the value method should throw a
user-defined unchecked exception.
The following code excerpt shows the recommended way to do that using a root solver as an example, but the same construct is applicable to ODE integrators or optimizers.
private static class LocalException extends RuntimeException {
// The x value that caused the problem.
private final SomeFieldType x;
public LocalException(SomeFieldType x) {
this.x = x;
}
public double getX() {
return x;
}
}
private static class MyFunction implements FieldUnivariateFunction<SomeFieldType> {
public SomeFieldType value(SomeFieldType x) {
SomeFieldType y = hugeFormula(x);
if (somethingBadHappens) {
throw new LocalException(x);
}
return y;
}
}
public void compute() {
try {
solver.solve(maxEval, new MyFunction(a, b, c), min, max);
} catch (LocalException le) {
// Retrieve the x value.
}
}
As shown, the exception is local to the user's code and it is guaranteed
that Apache Commons Math will not catch it.UnivariateFunctionT value(T x)
x - Point at which the function value should be computed.IllegalArgumentException - when the activated method itself can
ascertain that a precondition, specified in the API expressed at the
level of the activated method, has been violated.
When Commons Math throws an IllegalArgumentException, it is
usually the consequence of checking the actual parameters passed to
the method.Copyright © 2003–2016 The Apache Software Foundation. All rights reserved.