Re: Help: Switch constraints on or off

[Heinrich Schuchardt]

On 11/24/20 8:42 PM, Andrew Makhorin wrote:
> On Tue, 2020-11-24 at 18:59 +0000, Manuel Castro wrote:
> > Hi there,
> >
> > I am wondering how I can use an if statement to turn a constraint on
> > or off.
> > For example in my problem I have the following constraint:
> >
> > subject to linctr14 {i in PeriodsCount: i == 1}: StorageEnergy[i] =
> > (StorageStateCharge * StorageEnergyRating + ((StorageEfficiencyCharge
> > * (StoragePowerCharge[i])) - ((StoragePowerDischarge[i]) /
> > StorageEfficiencyDischarge)));
> >
> > Now, I only want to consider storage in my problem if an object
> > storage actually exists.
> > For that, I would have a StorageStatusFlag which if equal to "1" then
> > I would consider the constraint in my problem.
> > For example:
> >
> > If (StorageStatusFlag == 1) then
> >      subject to linctr14 {i in PeriodsCount: i == 1}: StorageEnergy[i]
> > = (StorageStateCharge * StorageEnergyRating +
> > ((StorageEfficiencyCharge * (StoragePowerCharge[i])) -
> > ((StoragePowerDischarge[i]) / StorageEfficiencyDischarge)));
> > end if

Just add the condition to the constraint iterator:

subject to
linctr14{i in PeriodsCount: i == 1 && StorageStatusFlag == 1}: ....

Best regards

Heinrich

> > This is what I used to do in "mosel" language from FICO Xpress (I
> > don't have a license anymore so I am discovering GLPK ). How can I do
> > this in GLPK language? What's the workaround that we can use for this?
>
>
> You could use the C preprocessor.
>
>
> > Many thanks in advance for your help. It's really appreciated.
> >
> > Kind regards,
> > Manuel.