Re: [Help-glpk] More conditional variables fun

[Yaron Kretchmer]

Yes, but since b,d,e,a are all variables I can't just multiply. 

Regards
Kretch

On Mon, Oct 12, 2009 at 1:53 PM, D'Agostino, Larry - TX <Larry.D'address@hidden> wrote:

Sorry for double posting.

 

Actually you might want to try something to the affect of

 

c <=  d*b + e*a

 

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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 D'Agostino, Larry - TX
Sent: Monday, October 12, 2009 3:42 PM
To: Yaron Kretchmer; help-glpk
Subject: RE: [Help-glpk] More conditional variables fun

 

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

 

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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