GAMS World Forum

Thanks Michael!

Hello,

Is there a way to execute the following condition when solving a model?
X and Y are compilation variables, and either one exists at a time.

Thanks,
Zamry

The alias definitely works but I'm still solving the entire timepoints in each loop. In a toy problem shown below, I'm expecting to solve only t1 in the first loop, and only t2 in the second loop. option LP = cbc; option limrow = 0; option limcol = 0; option solprint = off; option dispwidth = 20; Se...

Hi Fred, Thanks for replying. My rough idea to form the loop is as follows, loop(t, Solve Model using NLP minimizing z_obj; ); However, GAMS does not permit any controlling set inside the body of the loop since the scenario t constitutes the construct of my model. Seems like the only way to go for m...

Hello, I solve timeseries NLPs of 6 million variables in GAMS using the IPOPTH solver. The same model base is used for various objective analyses. The model is discretized at a 1 hr interval over a 24 hour duration. There exist some optional temporal constraints that link between subsequent timepoin...

Hi Michael, Thank you for this useful insight. My model is indeed huge, containing almost 23 million non-zero elements and 12 million nonlinear non-zero elements. Here is the model statistics: MODEL STATISTICS BLOCKS OF EQUATIONS 88 SINGLE EQUATIONS 6,674,951 BLOCKS OF VARIABLES 34 SINGLE VARIABLES ...

I'm solving large-scale non-convex NLPs that typically consist of 6-10 million equalities. On average, the model generation time is 10 min and the solve time is 15 min, so the model generation itself becomes a performance bottleneck. Some sets of equalities are complex and take a long time to genera...

Hello, I'm solving large-scale power flow problems (NLPs) in GAMS. On average, a problem consists of 5 million variables in which the model generation time alone takes about 10 min. My strategy involves two solve stages: Stage 1: solve model X (converged in 50 min), Stage 2: re-solve model X with so...

Thank you Michael. Your response cleared things up.

Zamry

Hello, I have an issue with the code block below. The logic $ifThenE cleanup_solve>0 picks up the original 0 value of the scalar, but not the updated value. Any suggestion to make the $ifThenE picking the updated postsolve value ? Scalar postsolve / 0 /; postsolve = card(devices); $ifThenE postsolve...