Re: [Help-glpk] is it possible to determine the value a nb variable will take?

[Michael Hennebry]

On Tue, 20 Jan 2009, Andrew Makhorin wrote:

[Michael Hennebry]
> > Thank you for the code.
> > I noticed that you used the lpx_warm_up function iteratively.
> > IIRC lpx_warm_up is good for setting an initial basis,
> > but is rather slow as a pivot mechanism.
> > I'm pretty sure it will refactor the basis from scratch every time.
>
> Lpx_warm_up computes the basis factorization only if it does not exist,
> i.e. if glp_bf_exists returns zero.

Does changing the status of a basic variable to
nonbasic cause glp_bf_exists to return nonzero?

> > That said, I'm not sure the API provides another mechanism for a custom
> > pivot.
>
> Yes, there must be added an api routine to update the factorization
> on changing the basis when a specified basic variable leaves the basis
> and a non-basic one enters it.

For what I have in mind, I need to specify
both the entering and leaving variables.

--
Michael   address@hidden
"Pessimist: The glass is half empty.
Optimist:   The glass is half full.
Engineer:   The glass is twice as big as it needs to be."