Re: [Help-glpk] Basis read/write

[prem swaroop]

Andrew / team

While I understand the reason why these features were removed, I was wondering 
whether these are scheduled to be re-introduced (without the limitations listed 
by Andrew of course) sometime in future.

The one release post my last mail (4.40) does not have these.

Thanks, regards
Prem

On Mon, Oct 26, 2009 at 6:39 AM, Andrew Makhorin <address@hidden> wrote:
> There #39;s a couple of features documented in 4.34 in the
> stand-alone solver section (Appendix D):

> (Options specifi c to simplex method)



> --bas fi lename read initial basis from  filename in MPS format

> --wbas fi lename write  nal basis to fi lename in MPS format

> Both are missing from the glpsol that I built on cygwin/Windows
> Vista, for versions 4.34 as well as 4.39.

> Now, documentation for 4.39 does NOT mention these features - so that
> #39;s at least consistent.

> I suspect this feature existed earlier on.  I think this could be a
> useful feature to keep, and I can quote my case here.

> I am essentially solving a large-ish LP whose parameters are
> generated by incrementing one parameter value.  And so, I dont expect
> too many changes in the solution for a large part of my increments,
> and hence using a final basis for one solution as an initial basis for
> the next could save a lot in time.



Options --bas and --wbas were temporarily removed from glpsol, since
they supported only fixed mps format. This made them useless in most
cases due to limitation of row/column name length to 8 chars (in
mathprog models the names produced by the translator are, as a rule,
longer).






Andrew / team

While I understand the reason why these features were removed, I was wondering whether these are scheduled to be re-introduced (without the limitations listed by Andrew of course) sometime in future.

The one release post my last mail (4.40) does not have these.

Thanks, regards
Prem

On Mon, Oct 26, 2009 at 6:39 AM, Andrew Makhorin <address@hidden> wrote:

> There #39;s a couple of features documented in 4.34 in the
> stand-alone solver section (Appendix D):

> (Options specifi c to simplex method)

> --bas fi lename read initial basis from  filename in MPS format

> --wbas fi lename write  nal basis to fi lename in MPS format

> Both are missing from the glpsol that I built on cygwin/Windows
> Vista, for versions 4.34 as well as 4.39.

> Now, documentation for 4.39 does NOT mention these features - so that
> #39;s at least consistent.

> I suspect this feature existed earlier on.  I think this could be a
> useful feature to keep, and I can quote my case here.

> I am essentially solving a large-ish LP whose parameters are
> generated by incrementing one parameter value.  And so, I dont expect
> too many changes in the solution for a large part of my increments,
> and hence using a final basis for one solution as an initial basis for
> the next could save a lot in time.

Options --bas and --wbas were temporarily removed from glpsol, since
they supported only fixed mps format. This made them useless in most
cases due to limitation of row/column name length to 8 chars (in
mathprog models the names produced by the translator are, as a rule,
longer).