Resolution: Won't Fix
Affects Version/s: 2.2
Fix Version/s: None
PolynomialSplineFunction is not Serializable, while the very similar PolynomialFunction class in the same package is. All that needs to be done is to add the import:
and change this:
public class PolynomialSplineFunction implements DifferentiableUnivariateRealFunction
public class PolynomialSplineFunction implements DifferentiableUnivariateRealFunction, Serializable
I made exactly that modification to a local copy and it serialized successfully. Before the change, I got serialization errors.