Hi Luc, I'll work on tests when I get a chance.
RealFieldElement has a lot of functions so its a bit out of my way. Cheers, -Ajo On Thu, Sep 19, 2013 at 10:58 AM, Luc Maisonobe <luc.maison...@free.fr>wrote: > Hi Ajo, > > Le 19/09/2013 16:26, Ajo Fod a écrit : > > Created: > https://issues.apache.org/jira/browse/MATH-1036#comment-13771933 > > This looks promising. Would it be possible to have this class implement > RealFieldElement<GradStructure> and to have some unit tests? > > best regards, > Luc > > > > > > > > > On Thu, Sep 19, 2013 at 12:29 AM, luc <l...@spaceroots.org> wrote: > > > >> Le 2013-09-19 08:26, Ajo Fod a écrit : > >> > >>> Hello, > >>> > >> > >> Hi Ajo, > >> > >> > >> > >>> Ran into problems with DerivativeStructure today. It requires a lot of > >>> memory with 6000 or so independent variables. I poked around and found > >>> it the problem starts with the number of DSCompiler objects > >>> instantiated. > >>> > >> > >> Yes, this is a know side effect of the ability to handle both several > >> variables > >> and several derivative orders. It is even worse when you combine medium > >> numbers > >> but along both axes (say 20 derivatives and 20 variables, I guess it is > >> almost > >> impossible to fir in memory of regular desktop computers). > >> > >> > >> > >>> Given this and my earlier observation that in sparse derivative trees, > >>> the existing structure allocates space for all independent variables > >>> and hence is computationally inefficient, I designed a > >>> faster/leaner(less memory) structure. > >>> > >>> One shortcomming of DS is that it computes only up to the first > >>> derivative. This may not be a problem in many cases such as the > >>> minimization of a multivariate function where optimization can be much > >>> quicker with a gradient. Going as far as the hessian may be > >>> fundamentally too memory or time intensive. So, it is useful to have > >>> an easier method to computing just the first derivative. > >>> > >> > >> This sound interesting, I hope it could be added as a more specialized > >> alternative. The name should probably be adapted to reflect it is > designed > >> for order 1 and many variables (perhaps DerivativeStructure1N or > something > >> like that). > >> > >> > >> > >>> The design of DS is that all DS instances created either as a results > >>> of calling: > >>> > >>> DS.getConst(value); // for constants > >>> > >>> DS.getVariable(idx, value); // for independent variables > >>> > >>> ... OR as a rest of some computation. > >>> > >>> I felt it appropriate to add an addInPlace and multInPlace for > >>> aggregation processes so that objects are not copied over too often. > >>> > >> > >> If you handle a really large number of variables at the same time, it > >> makes sense (same discussion as why general matrices and vectors are > often > >> not immutable). > >> > >> > >>> Attached is the code. > >>> > >> > >> Attachments are automatically stripped from messages sent to the list. > >> Small > >> code snippets can be written directly in the mail, but larger > >> contributions can > >> only be attached to JIRA issues (but still discussion occurs on the > list, > >> yes, > >> its cumbersome, we are sorry for that). > >> > >> Thank you very much for you interest in this field of differentiation. > >> > >> best regards, > >> Luc > >> > >> > >>> Cheers, > >>> Ajo > >>> > >>> > >>> > ------------------------------**------------------------------**--------- > >>> To unsubscribe, e-mail: dev-unsubscribe@commons.**apache.org< > dev-unsubscr...@commons.apache.org> > >>> For additional commands, e-mail: dev-h...@commons.apache.org > >>> > >> > >> > ------------------------------**------------------------------**--------- > >> To unsubscribe, e-mail: dev-unsubscribe@commons.**apache.org< > dev-unsubscr...@commons.apache.org> > >> For additional commands, e-mail: dev-h...@commons.apache.org > >> > >> > > > > > --------------------------------------------------------------------- > To unsubscribe, e-mail: dev-unsubscr...@commons.apache.org > For additional commands, e-mail: dev-h...@commons.apache.org > >
