Re: [Help-glpk] More conditional variables fun

[Yaron Kretchmer]

Thanks Larry. What I was looking for is for a way of forcing the "C" variable to equal values per the truth table. 

If "C" was binary I could achieve this by a series of inequalities without big M, and I'm just wondering what would be the formulation for non-binary variables.

Regards
Kretch

On Mon, Oct 12, 2009 at 1:41 PM, D'Agostino, Larry - TX <Larry.D'address@hidden> wrote:

Try thinking in terms of a Big M or large variable method.  For instance…

 

continuous variable _expression_  <  (some large number) (binary variable)

 

so you may do

 

_expression_ <= M * (a + b)

 

where M is a very large number

 

---

From: help-glpk-bounces+larry.d'agostino=gmacrescap.com@gnu.org [mailto:help-glpk-bounces+larry.d'agostino=gmacrescap.com@gnu.org] On Behalf Of Yaron Kretchmer
Sent: Monday, October 12, 2009 3:24 PM
To: help-glpk
Subject: [Help-glpk] More conditional variables fun

 

Hi There.
Using feedback I got from the mailing list, I was able to formulate binary conditional variables.

Now I'd like to be able to model conditional non-binary variables. Does anybody know how to formulate this in mathprog?

----------Begin Description -------------------
*) a,b are binary
*) c,d,e is continuous.
*) I'd like c to be
    - 0 if a=b=0
    - d if a=0,b=1
    - e if a=1,b=0
    - 0 if a=b=1
----------End Description


Thanks much
Kretch