> Betreff: Re: [Help-glpk] help
> Hello Daniele,
>
> the following model contains a constraint of the type you refer to.
> Please, read glpk-4.47/doc/gmpl.pdf carefully. It is included in the
> source distribution of GLPK available at
>
ftp://ftp.gnu.org/gnu/glpk/glpk-4.47.tar.gz
>
> param R;
> param T;
> param t;
> set Q := { 1..T };
> set W;
> param r{W};
> param d{W};
> var x{W,Q}, >= 0, <=10;
> maximize objective:
> sum{i in W, q in Q} x[i,q];
> s.t. constraint:
> sum{i in W} sum{q in Q : q >= t-d[i] && q <= t-1} r[i] * x[i,q] <= R;
> data;
> set W := a b;
> param R := 10;
> param T := 5;
> param t := 6;
> param d :=
> [a] 2
> [b] 3;
> param r :=
> [a] .5
> [b] .7;
> end;
>
> Best regards
>
> Xypron
> -------- Original-Nachricht --------
> > Datum: Wed, 27 Jun 2012 11:02:27 +0200
> > Betreff: Re: [Help-glpk] help
>
> > 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
> >
> > Thanks
> >
> >
> > 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
> > >
> > > Xypron
> > >
> > > -------- 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
i.th 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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