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by bussieck
10 hours ago
Forum: Solvers
Topic: Computational time of model extremely increased
Replies: 4
Views: 81

Re: Computational time of model extremely increased

GAMS/Cplex (in default mode) runs deterministically when executed on the identical model instance on the same machine. There are a few options that can make it behave non-deterministically (only with option thread<>1). But even slight changes (e.g. the order of variables and equations, or a coeffici...
by bussieck
12 hours ago
Forum: Solvers
Topic: how to reduce memory use of cplex
Replies: 3
Views: 322

Re: how to reduce memory use of cplex

It is not Cplex that runs out of memory, it is GAMS. You can try to clear some unset large parameters (option clear=sym;) but Cplex will most likely require a multiple of the memory used by GAMS. So rent a bigger machine. There are plenty of cloud offering that give you access to machines with plent...
by bussieck
3 weeks ago
Forum: Modeling
Topic: Simple Equilibrium problem with non-linear equations - division by zero
Replies: 2
Views: 63

Re: Simple Equilibrium problem with non-linear equations - division by zero

I think the GAMS error messages are quite useful: **** Exec Error at line 6: division by zero (0) Line 6 reads: 6 demand.. qd =e= beta/(p**ed) ; GAMS variables have there default level at 0. So move p.l away from 0: p.l=1; Next you get: **** Unmatched variable not free or fixed qs Qs is a positive v...
by bussieck
4 weeks ago
Forum: Modeling
Topic: Problem with ignoring GAMS constraints
Replies: 4
Views: 65

Re: Problem with ignoring GAMS constraints

Did you check the model/solve status before you report things back to Excel? The solver might have told you that the model is (locally) infeasible.

-Michael
by bussieck
4 weeks ago
Forum: Solvers
Topic: CPLEX time vs resUsd
Replies: 5
Views: 102

Re: CPLEX time vs resUsd

The resUsd includes time to set up the model in Cplex and to report the solution to GAMS. For quadratic models it also included the time to extract the Q matrices from the non-linear instructions. Usually the time between resUsd and the time Cplex reports in the log is small and of not much practica...
by bussieck
1 month ago
Forum: Syntax
Topic: excel to gams Topic is solved
Replies: 8
Views: 234

Re: excel to gams Topic is solved

If you look at the content of the GDX file it will be pretty obvious that the read did not succeed as you planned: C:\Users\Michael\Downloads>gdxdump Daten-TSP.gdx $onempty Parameter d(*,*) / 'j2'.'0' 8.9, 'j2'.'2.2' 9.3, 'j2'.'1.8' 10.5, 'j2'.'10.1' 11.4, 'j2'.'0.6' 8.6, 'j3'.'0' 2.3, ... Problem i...
by bussieck
1 month ago
Forum: Syntax
Topic: excel to gams Topic is solved
Replies: 8
Views: 234

Re: excel to gams Topic is solved

You should check the return code after a $call and you should load data with $loadDC to make sure that you don't leave record behind. $call GDXXRW.exe Daten-TSP.xlsx trace=3 par=d rng=Tabelle1!A2 rdim=1 cdim=1 $if errorlevel 1 $abort problems with gdxxrw $GDXIN Daten-TSP.gdx $LOADDC d Hope this help...
by bussieck
1 month ago
Forum: Modeling
Topic: Quadratic constrained convex problem Topic is solved
Replies: 2
Views: 51

Re: Quadratic constrained convex problem Topic is solved

Not sure what you mean. If I solve this with a global solver like Antigone, Baron, Couenne, LindoGlobal, or SCIP (since this is a non-convex QCP) I get a good solution: LOWER LEVEL UPPER MARGINAL ---- VAR OF -INF 4.472 +INF . ---- VAR x1 -INF 0.011 +INF . ---- VAR x2 -INF 4.472 +INF . Not sure what ...
by bussieck
1 month ago
Forum: Syntax
Topic: excel to gams Topic is solved
Replies: 8
Views: 234

Re: excel to gams Topic is solved

Hi, Writing to an open workbook is possible but very much discouraged. You need to share you workbook (see https://support.office.com/en-us/article/About-the-shared-workbook-feature-49b833c0-873b-48d8-8bf2-c1c59a628534). Problem is that you only see the changes after "saving" the open work...
by bussieck
1 month ago
Forum: Announcements
Topic: GAMS Distribution 24.9.1 Announcement
Replies: 0
Views: 92

GAMS Distribution 24.9.1 Announcement

Hi GAMS Users,

We started distributing GAMS Release 24.9.1 on August 30,2017

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

Here are the release notes: https://www.gams.com/latest/docs/RN_249.html

-Michael

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