Re: DAE daspk solver problem

[Sebastian Schöps]

Lazy_Tom wrote
> I don't know why DAE solvers index capabilities are not reported in Octave
> manual. Matlab at least tells you that you can go no further than index 1
> (at least without doing some "magic"...)

You are right. Feel free to oben a bug report at savannah, maybe immediately
suggesting a string that can be added to the help. However, I assume that
dassl and daspk will be deprecated in some future version since we are
moving to odeXY compatible solvers. 


Lazy_Tom wrote
> about the paper you cited, yup, I'm aware of it and I agree, it is quite
> nice. 
> Well, at least I'll gave it a try, I think that for DAE problems I'll move
> to openModelica

I think that ode5r from odepkg should be able to solve index3 problems since
its based on Radau 5 [1]. We hope to have a new release of odepkg quickly
after Octave 4.2. I will keep in mind to include such information in the
help.

Regarding openModelica: yes, they do some clever tricks for higher index. As
far as I recall it's based on dummy derivatives [2]. Such stuff is easier
for modelica since it is in some sense a symbolic language. However, to my
best knowledge, it is not really well suited for big problems. So, as usual,
the best choice depends on what you want to do :)

Seb.

[1] http://www.unige.ch/~hairer/prog/stiff/radau5.f
[2] http://dx.doi.org/10.1137/0914043



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