Search found 10 matches

by mbh
1 month ago
Forum: Modeling
Topic: linearization of a logarithmic function (log) defined over a variable
Replies: 1
Views: 174

linearization of a logarithmic function (log) defined over a variable

Hi all,
I there anyway to linearize a logarithmic function (log) defined over a variable in GAMS?

Thank you for your help.
by mbh
4 months ago
Forum: Modeling
Topic: "Couenne finished. No feasible point found."
Replies: 0
Views: 474

"Couenne finished. No feasible point found."

Hi all, I am trying to run an MINLP model with Couenne . But I keep getting this message that "Couenne finished. No feasible point found." Model solve summary also reports RESOURCE INTERUPT and 14 NO SOULTION FOUND. However, I am able to find some locally optimum solution using Dicopt. Does it mean ...
by mbh
6 months ago
Forum: Modeling
Topic: Problem with loop in MINLP model.
Replies: 1
Views: 313

Problem with loop in MINLP model.

Hi all, I have a MINLP model which I try to do sensitivity analysis in a loop. I set the starting point into the loop. Now I have a problem that the results that I get using the loop are different from the results of corresponding scenario but without a loop. For example, some times the model with t...
by mbh
7 months ago
Forum: Modeling
Topic: How to use loop to run model several times when some random data is being imported from excel.
Replies: 2
Views: 388

How to use loop to run model several times when some random data is being imported from excel.

Hi All, I import some random data from excel into GAMS. So every time that I run the model the results change because the random numbers change. I'd like to use a loop to rum the model several times by that loop rather than running manually. I would appreciate it if anyone can help me. Sorry if the ...
by mbh
7 months ago
Forum: Syntax
Topic: logical equations & binary variables
Replies: 18
Views: 3323

Re: logical equations & binary variables

Hi again Manassaldi, I have a new question for you and will really appreciate it if you can help me as before. I am still struggling with these kind of logical conditions on endogenous variable in my model. The problem is that p(n) includes a binary variable itself. I mean p(n) = sum(g, t(g) * c(g,n...
by mbh
7 months ago
Forum: Solvers
Topic: Couenne solver error: " Equation 47 is general nonlinear: function vcPower results in a nonlinear expression"
Replies: 1
Views: 384

Couenne solver error: " Equation 47 is general nonlinear: function vcPower results in a nonlinear expression"

Hi all, I have a MINLP model and am using Couenne solver. The solver gives me some errors. The error message are: " Equation 47 is general nonlinear: function vcPower results in a nonlinear expression". From this error message I have no clue what is the reason of the problem. Can anyone help me on t...
by mbh
7 months ago
Forum: Modeling
Topic: Nonlinear constraints in MINLP model
Replies: 2
Views: 359

Nonlinear constraints in MINLP model

Hi all, I have a mixed integer non linear model and now I am trying to reduce the number of nonlinear constraints because the model is very big and I keep getting infeasibilities or errors. Two of the constraints that are non linear are as following: const11(n).. p(n) =e= 1 - (1 + (d(n) / 229)) ** (...
by mbh
8 months ago
Forum: Syntax
Topic: logical equations & binary variables
Replies: 18
Views: 3323

Re: logical equations & binary variables

Hi Manassaldi.
Thank you so much for helping me out. Your analysis was really helpful.

Best,
Mary
by mbh
8 months ago
Forum: Syntax
Topic: logical equations & binary variables
Replies: 18
Views: 3323

Re: logical equations & binary variables

Hi all, I have a question regarding logical conditions applied to choice variables. I will be happy if someone, specially Manassaldi, can help me on that. I have two choice variables, a(n) and th, and a parameter p(n). I need to code the following logic in gams. if p(n)<= th then a(n) =0; else if th...