[Coin-discuss] feeding Symphony solutions on the fly

[Michael Hennebry]

On Wed, 19 Jan 2005, Ted Ralphs wrote:

> Michael Hennebry wrote:
> > Suppose one has a procedure for converting a
> > fractional solution into a feasible solution.
> >
> > Where would be a good place to put such a procedure?
> > How would one tell Symphony about a new solution?
>
> Currently, there is no direct interface for the user to pass solutions
> back to SYMPHONY. However, SYMPHONY does have an internal mechanism for
> calling a primal heuristic and incorporating new solutions on the
> fly---take a look at the block of code starting at line 635 of the file
> LP/lp_wrapper.c. This is where SYMPHONY calls its primal heuristic
> (borrowed from CBC). You could fairly easily add your own heuristic here
> if you want to and pass solutions back to SYMPHONY. A better solution is
> for me to extend the callback interface to add a callback for executing
> a primal heuristic. This would be called right after the current
> solution is checked for feasibility in each iteration. Does this make
> sense? I will add this callback in the next few days and let you know.

Thanks.
My first IP solver, I wrote from scratch and XMP.
The motivation behind my rounding algorithm was
not to improve efficiency, but to provide protection
from the ravages of floating point arithmetic.
I suspect that that is still a worthy purpose.

-- 
Mike   hennebry at web.cs.ndsu.NoDak.edu
"Our gods are dead.  Ancient Klingon warriors slew them
... they were more trouble than they were worth."          --  Worf