Hi Luc, > > Yes, all FieldElement are expected to be numbers, or at least there is > an homomorphism mapping the elements to numbers. However, FieldElement > cannot implement Number because number is a class, not an interface. If > we want to have this hierarchy, we also have to change FieldElement to > an abstract class. > Ooops, I missed that
> > This interface was introduced in order to have one common ancestor > between Fraction and BigReal. This common ancestor then allowed > trivially to support some important linear algebra algorithms on > fractions by just slightly adapting what did exist for BigReal. > That's exactly the reason why I use FieldElement (in my case : multipole expansions). > > This interface was not intended as a step towards complete algebra > support. There have been some questions about that, but we chose to not > go this way (at that time), as we still have very limited resources. We > do not have Group, AbelianGroup or Ring interfaces for example. > Also agreed. Interfacing with JAS would be an option (see recent posts). Maybe in the (not so near) future 5.0, 6.0 ;) ? > > There was also a Jira issue about adding more operations (typically > sqrt, which would for example allow support for Cholesky decomposition). > See <https://issues.apache.org/jira/browse/MATH-569>. This would clearly > imply at least one additional interface level since for example sqrt is > not an internal operation for fractions. We finally decided not to > implement this, as the initial need was limited to Complex only. > > I am slightly reluctant to change FieldElement to an abstract class. > What do other people think about this ? > > Luc > I see your point and was going to suggest that we only add a doubleValue() method to the interface FieldElement. But that does not work with Complex! So I'll have to think of something else... Sébastien --------------------------------------------------------------------- To unsubscribe, e-mail: dev-unsubscr...@commons.apache.org For additional commands, e-mail: dev-h...@commons.apache.org
