Hi @QueraltA ,

Hope all is well.

Did @mohansx and @gdiepen 's answers help you to move forward?

Thanks for getting back to us!

@QueraltA 

if you need only the roundUp value, you could even just do the below. 

total_power_plants_integer >= total_power_plants

Include total_power_plants_integer to your objective function, with a minimize direction. If your problem is a minimization, then obj + total_power_plants_integer and if it is a maximization problem, then obj - total_power_plants_integer. 

Regarding the “postsolve indicates solution is unreliable” warning, can you review this thread on our (deprecated) google groups forum ? https://groups.google.com/g/aimms/c/67sYx0ZHFMo/m/sUWlkLe_0dIJ

Setting the integrality option to 1 should work in most cases. 

You can also review this post to improve the scaling of your model: Marcel Hunting on the AIMMS Scaling tool | AIMMS Community

Thanks a lot for your answer. I have changed my model and now, due to these changes, I want to have the top value of total_power_plants.  I have solved it as follows:

total_power_plants_integer = total_power_plants + aux1

Where total_power_plants_integer is an integer variable and the range of aux1 is 0,1]. Generally, this solution works but when “total_power_plants” is an integer value I want to keep its value. For instance:

total_power_plants = 10

I want:

total_power_plants_integer=10

aux1=0

I tried to solve this problem changing the aux1 range: n0,1) but the solution with AIMMS was:

Warning: Postsolve indicates that solution to funciton_objetive is not reliable (see message window).

And the solution obtained does not make sense because some variables were outside their bounds.

@QueraltA , do you always want to use the rounded down value ? 

Is the variable total_power_plants involved in other constraints ? Where is the value 2.7 coming from ? 

Something like total_power_plants = sumsindex_plants, power(index_plants)] .. 

I believe the approach in Model a Rounded Variable — AIMMS How-To should work in your case, can you elaborate how it does not fit your needs ? 

If you only need the rounded down value, you could even drop the auxilliary variable aux1 and just have var1 = value - aux2 as your constraint. Set the range of aux2 as o0,1] and the integer variable var1’s will be equal to rounddown(value). 

Thanks for your quick response. You are right, we only can have a integer number of power plants but I can’t set the range of this variable to integer because it is calculated from the production of the plant and this variable doesn’t have to be integer.

Looking at the variable name, I am assuming you cannot have 0.7 powerplants (it is either 0, or 1, or 2, etc).

In your case, you can set the range of the variable total_power_plants to integer and this should result in the variable only taking integer values.