use bound or constraint?

[Archiver]

Hi,

i try to set a variable at serveral times to a calculated value ( F(t)$
(....) = F(t-24) ....). I have a set t /1*168/ and i want to set a
variable F for certain t to F(t-24). I try this with bounds

F.fx$(...) = F.l(t-24) ...

but i assume that F.l is more a startpoint as the level of variable F
so the result will be 0. Then i try a constraint like

equ$(....) F(t) =e= F(t-24) ... but till this time i dont get a
solution.

So, what would be the best way ... solve this problem with bounds or
constraints? I wounder if you can give me an advice in which way i
should go on.

kr

michael
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[Archiver]

Michael,

You clearly need a constraint! You write that you don't get a solution
after adding the constraint. Why don't you get a solution? Does the
solver declare the problem infeasible? If so, you need to work on
resolving the infeasibility.

Regards,
Michael Bussieck - GAMSWorld Coordinator

On Dec 10, 4:19 pm, mic wrote:
> > Hi,
> >
> > i try to set a variable at serveral times to a calculated value ( F(t)$
> > (....) = F(t-24) ....). I have a set t /1*168/ and i want to set a
> > variable F for certain t to F(t-24). I try this with bounds
> >
> > F.fx$(...) = F.l(t-24) ...
> >
> > but i assume that F.l is more a startpoint as the level of variable F
> > so the result will be 0. Then i try a constraint like
> >
> > equ$(....) F(t) =e= F(t-24) ... but till this time i dont get a
> > solution.
> >
> > So, what would be the best way ... solve this problem with bounds or
> > constraints? I wounder if you can give me an advice in which way i
> > should go on.
> >
> > kr
> >
> > michael
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[Archiver]

Hi Michael,

thanks for your reply. You are right ... it works now.

On 11 Dez., 10:03, Gamsworld Admin wrote:
> > Michael,
> >
> > You clearly need a constraint! You write that you don't get a solution
> > after adding the constraint. Why don't you get a solution? Does the
> > solver declare the problem infeasible? If so, you need to work on
> > resolving the infeasibility.
> >
> > Regards,
> > Michael Bussieck - GAMSWorld Coordinator
> >
> > On Dec 10, 4:19 pm, mic wrote:
> >
>> > > Hi,
> >
>> > > i try to set a variable at serveral times to a calculated value ( F(t)$
>> > > (....) = F(t-24) ....). I have a set t /1*168/ and i want to set a
>> > > variable F for certain t to F(t-24). I try this with bounds
> >
>> > > F.fx$(...) = F.l(t-24) ...
> >
>> > > but i assume that F.l is more a startpoint as the level of variable F
>> > > so the result will be 0. Then i try a constraint like
> >
>> > > equ$(....) F(t) =e= F(t-24) ... but till this time i dont get a
>> > > solution.
> >
>> > > So, what would be the best way ... solve this problem with bounds or
>> > > constraints? I wounder if you can give me an advice in which way i
>> > > should go on.
> >
>> > > kr
> >
>> > > michael
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