Re: Help: Switch constraints on or off

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.
>>
>