Date:         Fri, 16 Dec 2005 16:56:09 -0800
Reply-To:     David L Cassell <davidlcassell@MSN.COM>
Sender:       "SAS(r) Discussion" <SAS-L@LISTSERV.UGA.EDU>
From:         David L Cassell <davidlcassell@MSN.COM>
Subject:      Re: Help with PROC LP, integer program initial solution
In-Reply-To:  <200512160302.jBFNWP5d029302@malibu.cc.uga.edu>
Content-Type: text/plain; format=flowed

dwoodsnz@GMAIL.COM wrote:
>Thanks for the tips. The problem is IP, with some integer and some
>binary variables.  I'm not familiar with the term "driving
>coefficients", I've been using the BINARY and INTEGER types of row to
>specify the variables.
>
>The _ORLP_ macro variable isn't telling me anything interesting.
>
>I've tried using the PRIMALIN method, but I'm having trouble putting my
>initial solution into the right format, if anyone has any tricks on
>that let me know. It's years since I've done any math programming, so
>trying to find which variables are basic and which are just at their
>upper bound is beyond me.  I tried creating a new problem which set all
>the variables to their values in the optimal solution, and using the
>PRIMALOUT from that as a PRIMALIN to a modified problem where the new
>constraint is not binding, but it just told me that the basis in the
>PRIMALIN data set is singular!  Not quite sure why that is or what it
>means.
>
>I'd really prefer to use the BASIC type if I could get that working...
>it seems to be the option designed for this purpose.

Hmmm.  You took the PRIMALOUT= data set, and fed it in as a new PRIMALIN=
data set, and PROC LP told you that the basis was singular?  Did the &_ORLP_
macro variable tell you the same thing?

Is it possible you have over-specified your model?

David
--
David L. Cassell
mathematical statistician
Design Pathways
3115 NW Norwood Pl.
Corvallis OR 97330

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