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Re: [Help-glpk] help

From: glpk xypron
Subject: Re: [Help-glpk] help
Date: Wed, 27 Jun 2012 01:30:48 +0200

Hello Daniele,

from your description it is unclear what you mean by t.

Is t the run parameter of the summation or is it a parameter controlling the 
boundaries of the summation? It cannot be both.

Please, write down your equation completely including the definition of the 
sets and parameters. Either send it in tex or append an image file.

Best regards


-------- Original-Nachricht --------
> Datum: Tue, 26 Jun 2012 23:46:10 +0200
> Betreff: Re: [Help-glpk] help

> Re: [Help-glpk] help
> r (i) is a parameter and represents the resource request from the i-th
> activities by the system.
> The variable is x (i, t) where i is the index of the activities of the
> whole W and t is the index of the time interval.
> R is the total available resource is not exceeded while d (i) is the
> duration of the activity
> >
> >
> >
> >> On Tue, 26 Jun 2012, Daniele Micarelli wrote:
> >>
> >>  I have to solve a linear programming problem with the language and I'm
> >>> planning mathprog
> >>> I have difficulty writing the following constraint: ΣΣ r (i) * x (i,
> t)
> >>> <= R
> >>> where the first summation is true for all belonging to the W and the
> >>> second
> >>> summation has as its lower end t-d(i) and upper bound as t-1
> >>>
> >>
> >> You've not made it clear what is a variable and what is not.
> >> If r and x are both variables, you are done.
> >> *Linear* programming does not involve products of variables.
> >>
> >> --

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