On Fri, Jun 04, 2010 at 10:53:45AM -0400, John W. Eaton wrote: > On 3-Jun-2010, Jake wrote: > > | 1. Is there a reason why these functions haven't already been implemented? > | Lack of information on the algorithms, perhaps? > > Or, given that we have other ODE/DAE solvers that are quite good, no > compelling reason other than compatibility to write them? > > | 3. Are there any reasons why I shouldn't try to implement these functions? > > I think it would be fine to have them, and even include them in the > core Octave distribution. For that to happen, the code should follow > Octave's coding conventions, and it is essential that the work be > independent of Matlab, so you must not base your implementation on the > Matlab functions in any way, other than making the interface > compatible. > > In the past, when I've needed the odeNM functions for compatibility, > I've used wrapper functions for lsode or daspk that provide the odeNM > interface. That works well enough for me that I haven't had the need > to actually have the odeNM functions that use the same class of > algorithms used in the Matlab functions. I haven't included my > wrapper functions in Octave because they've never been complete > implementations. > > Is it necessary to have odeNM functions that use the same algorithms > as the corresponding Matlab functions, or is it sufficient to simply > provide the same interface while using some other algorithm to solve > the same problem. If the latter, then wrappers around lsode and daspk > might be easier to implement.
Though I always preferred lsode and the builtin DAE solvers for real work, there might be reasons to have Runge-Kutta ODE sovers available, e.g.: I'm not an expert on problems with PDEs, and it would take me some time to refresh the details, but I remember that for some special types of these problems there are established algorithms which (at least usually) employ fixed time-step ODE solvers. Furthermore, there is some convergence theory available for some of these algorithms which specifically addresses the employment of Runge-Kutta solvers. Sorry for being so inexact ... Olaf ------------------------------------------------------------------------------ ThinkGeek and WIRED's GeekDad team up for the Ultimate GeekDad Father's Day Giveaway. ONE MASSIVE PRIZE to the lucky parental unit. See the prize list and enter to win: http://p.sf.net/sfu/thinkgeek-promo _______________________________________________ Octave-dev mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/octave-dev
