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Re: [Help-glpk] help

From: Daniele Micarelli
Subject: Re: [Help-glpk] help
Date: Wed, 27 Jun 2012 11:02:27 +0200

Re: [Help-glpk] help

I have attached the image so it is clearer
W is a set of tasks
T is the set of the time allowed
r (i) is the parameter of the requested resource the activity i-th
d (i) is the duration of the i-th activity
R is the parameter that represents the total resource available in the system
X (i, q) is the variable


2012/6/27 glpk xypron <address@hidden>
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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