Re: Updated odeset/odeget

[rik]

On 10/17/2015 04:41 AM, Carlo De Falco wrote:
> On 16 Oct 2015, at 20:26, Rik <address@hidden> wrote:
>
>> The non-Matlab compliant options have been removed.  See this changeset 
>> (http://hg.savannah.gnu.org/hgweb/octave/rev/00caf63edcdf).
> I think your changeset makes the functions integrate_constant and 
> integrate_n_steps
> useless as there is now probably no way to trigger their use through the 
> options.

Not useless.  Unrecognized options can still be set, and Octave will only
print a warning, but otherwise pass the option through.  In ode45.m the
decision on which algorithm to use is based on the options TimeStepNumber
and TimeStepSize.  Even before removal, odeset() would have returned empty
entries by default for these fields resulting in the adaptive algorithm
being chosen.  Just as before, one will have to specifically set these
options with opts = odeset ("TimeStepNumber", XXX, "TimeStepSize", YYY) in
order to get a different solver.  The only change will be the warning,
"odeset: unknown field 'TimeStepNumber' in ODE options".


>
> Do we want to support that behaviour, even though it is not present in Matlab?
> Maybe Sebastian's proposal to have an (non compatible) option to pass a list 
> of fixed time steps to use for integration is easier to support and more 
> useful?

I can't answer these questions as my perspective is only about how to bring
the ODE code into the core.  Generally, however, we like to think of Octave
as a superset of Matlab; It should be able to do everything Matlab does,
but it certainly is okay to do more.

--Rik