Search found 480 matches

by bussieck
2 days ago
Forum: Modeling
Topic: Clearing the declarations between solving the models.
Replies: 2
Views: 53

Re: Clearing the declarations between solving the models.

Hi, There is no good way to start from scratch after you compiled a significant piece of code. Your scenarios might be close enough (in terms of domain sets etc) that this can be accomplished with lots of $clear and $onMulti (see https://www.gams.com/latest/docs/UG_DollarControlOptions.html) but it ...
by bussieck
6 days ago
Forum: Syntax
Topic: Change dimension
Replies: 3
Views: 187

Re: Change dimension

Sure. But you should understand the GAMS code yourself. It you understand what it does the change is trivial: set HUD /HUD02,HUD10,HUD15,HUD20/; set IUD /IUD15,IUD20/; set himap(HUD,IUD) / HUD15.IUD15,HUD20.IUD20 /; parameters test(HUD,IUD) / HUD02 .IUD15 15 HUD10 .IUD15 20 HUD10 .IUD20 30 /; parame...
by bussieck
1 week ago
Forum: Syntax
Topic: Change dimension
Replies: 3
Views: 187

Re: Change dimension

If there are not so many IUD elements, make a map between the IUD and the corresponding HUD (himap) and use this to create the new parameter: set HUD /HUD02,HUD10,HUD15,HUD20/; set IUD /IUD15,IUD20/; set himap(HUD,IUD) / HUD15.IUD15,HUD20.IUD20 /; parameters test(HUD,IUD) / HUD02 .IUD15 15 HUD10 .IU...
by bussieck
1 week ago
Forum: API
Topic: Problem occurred when trying to load embpycclib
Replies: 1
Views: 194

Re: Problem occurred when trying to load embpycclib

Can be many things. For example, missing C run-time system. One would need much more information (OS, OS version, GAMS version, ...) I suggest you write to GAMS' support and provide license information.

-Michael
by bussieck
1 week ago
Forum: Modeling
Topic: why can the feasible problem not find solution
Replies: 1
Views: 130

Re: why can the feasible problem not find solution

Without something to reproduce there is nothing to do. -Michael
by bussieck
1 week ago
Forum: Syntax
Topic: How to loop over sub-folders
Replies: 2
Views: 135

Re: How to loop over sub-folders

Embedded Python is your friend: $call test -d dir1 || mkdir dir1 $call test -d dir2 || mkdir dir2 $call test -d dir3 || mkdir dir3 $onechoV > listdir.gms display "%1"; $offecho $onEmbeddedCode Python: import os dirs = [ root for root, dirs, files in os.walk(os.path.normpath(r"%gams.wdir% ".rstrip())...
by bussieck
1 week ago
Forum: Solvers
Topic: Save CPU time when running a model for multiple times
Replies: 3
Views: 180

Re: Save CPU time when running a model for multiple times

If you know all the binary variable fixings ahead of time you can use GUSS: https://www.gams.com/latest/docs/S_GUSS.html. GUSS generates the model once and solves for many different "scenarios". If the outcome of solve n-1 impacts the bound setting of solve n you can't use GUSS. You can use GAMSMode...
by bussieck
1 week ago
Forum: Modeling
Topic: Using solution of one model as upper/lower bound in that model again - Global Optimization
Replies: 1
Views: 87

Re: Using solution of one model as upper/lower bound in that model again - Global Optimization

Be careful with "helping" an algorithm with bounding scheme (like branch-and-bound) with bounds. For minimization problem only set an upper bound (or even better provide a feasible solution). Never set the the lower bound. (opposite for maximization problems). Setting a "helping" lower bound deprive...
by bussieck
1 week ago
Forum: Announcements
Topic: GAMS Distribution 31.2.0 (Minor Release)
Replies: 0
Views: 51

GAMS Distribution 31.2.0 (Minor Release)

Hi GAMS Users,

We started distributing GAMS Minor Release 31.2.0 on June 19, 2020.

You can download the software from https://www.gams.com/download/

Here are the release notes: https://www.gams.com/latest/docs/RN_31.html#RN_3120

Your GAMS Team
www.gams.com
by bussieck
2 weeks ago
Forum: Solvers
Topic: Conopt all local optimum
Replies: 1
Views: 170

Re: Conopt all local optimum

No. You might try MSNLP (with Conopt as a subsolver). MSNLP is a multi-start method that starts a local solver from many points. MSNLP can report all the distinct locally optimal solutions (https://www.gams.com/latest/docs/S_MSNLP.html#MSNLP_LOCALS_FILE) it finds, no guarantee for getting all for th...