Dear all,
I am trying to use bratio in my model to pass the basis as a starting point of another model.

In this GAMS mode (https://drive.google.com/file/d/1wad9qO1h7M1kGbST64QxgcyJnb91HvsH/view?usp=sharing), I am trying to solve the first part of the model comprising of the obj fn, c1, c2 and c3 constraints. In the second part, I am trying to use the basis obtained from the first part to solve the problem with little or no computational effort. The second part of the model comprises of the objective function and constraints c4, c5 and c6 (These constraints are similar to c1, c2 and c3 but with a slightly changed RHS).

But, I see that both the parts of the problem take 3 iterations to solve which shouldn’t be happening as per my assumption.
Am I understanding something wrong here?

Hello Renger,
I checked the ITERATION COUNT in the lst file. It was 3 for both parts. Am I understanding this correctly?
Kindly let me know.
Thank you.

Hello Renger,
Thank you so much for your reply.
I want to mention here that constraints 1, 2 and 3 were the original model and I did the sensitivity analysis on this model to find the ranges within which if I change the RHS of the constraints, the model will have the same basis. I applied the 100% rule and changed the RHS of the three constraints to ensure that the model remained in the same basis.
That’s the reason when I passed the basis using ‘bratio’ from the first part of the model to the other, I expected the second part to solve in one iteration only. This is also the reason I thought that I hadn’t used ‘bratio’ correctly.
Does this sound logical to you?
Thank you!

Basis information is stored not only in GAMS variables but also in GAMS equations. For example, if you resolve the same model, it uses 0 iterations. Here’s some code to do that: