[Bonmin] bonmin and ampl external function

[Andreas Waechter]

Hi Roy,

Please keep replying to the mailing list, since other users might also be 
interested to get the follow up or might be able to help.

> I don't think my bonmin executable works with AMPL's user defined external
> function properly now, because it seems the external function works well
> when I test it using some fixed value as input variables in AMPL, however,
> when I tried to take it as a function and build a model in ampl using bonmin
> to solve it, it doesn't work. I think this is very strange.

Please verify that the external function is coded so that it can provide 
both first and second derivatives besides the function value itself, 
otherwise it won't work.

If you found out that your code also computes the derivatives, please 
submit a ticket at the Bonmin Trac page.  Include the information 
necessary to reproduce the problem, possibly including your code for the 
external function (or a pointer where to get it).

> By the way, could you tell me how to use my external function from AMPL
> interpreter?

I meant the program that comes up when you type 'ampl', so I assume that 
you already have tested it and it seems to be working.  But as for as I 
know that only asks for the function value from the external function.  I 
don't know how you could test that also first and second derivatives are 
provided.

Regards,

Andreas