[Os-project-managers] NaN in xs:double (OSrL)

[Kipp Martin]

Hi Gus:
> 
> That is not how I remember the discussion from last time (or maybe the 
> time before that):
> 
> <initialVariableValues numberOfVar="2">
>     <var idx="0" value="NaN"/>
>     <var idx="1"/>
> 
> should set both x0 and x1 to NaN (this I am clear on) and should send 
> those values to the solver (this is how I understood the discussion, but 
> perhaps I misunderstood).

No we don't send those values on to the solver, we send those to the OS 
solver interface. Consider Ipopt. We never give Ipopt a starting value 
of NaN for a variable. However, the OS Ipopt solver interface 
"intercepts" the NaN and replaces it with  1.7171. So we never send NaN 
to a solver.
> 
> But even then, I maintain that diagnosing a solver error would be 
> greatly helped if there were some mechanism that allows the user to 
> pinpoint the variable or constraint or even objective that went awry.
> And the only way I see for that to happen is a way that allows the 
> solver to return NaN to the user.

Yes, I can see your point. But this may all be for naught. Can you come 
up with an actual example where the solver actually returns a NaN? I 
mean THE solver, not the interface.

Cheers


> 
> Another Can$ 0.02
> 
> Cheers
> 
> gus
> 
> 


-- 
Kipp Martin
Professor of Operations Research
and Computing Technology
Booth School of Business
University of Chicago
5807 South Woodlawn Avenue
Chicago, IL 60637
773-702-7456
kmartin at chicagobooth.edu
http://www.chicagobooth.edu/faculty/bio.aspx?person_id=12825325568
http://projects.coin-or.org/OS