Search found 23 matches

by Lutz
1 week ago
Forum: Tools
Topic: GDXXRW - writing to excel - no header
Replies: 3
Views: 60

Re: GDXXRW - writing to excel - no header

Hi,

if it is about getting the values into the right place, you might want to use the "merge" option of gdxxrw, like described here: https://www.gams.com/latest/docs/T_GDXX ... HEET_MERGE

Best,
Lutz
by Lutz
5 months ago
Forum: Modeling
Topic: Lindo error in stochastic programming
Replies: 2
Views: 224

Re: Lindo error in stochastic programming

Hi, I found a few (formatting) problems in your emp.info file: - You missed a line break before the last line - traffic_sc does not exist in the model, you should not mention it as stage 2 symbol - You did not name the random variables in the loop, but put in some numbers instead According to these ...
by Lutz
5 months ago
Forum: Modeling
Topic: Can GAMS do random sampling from given dataset?
Replies: 2
Views: 229

Re: Can GAMS do random sampling from given dataset?

Hi, You can try something like this: Set scen /s1*s5/; Parameter Dataset(scen) / s1 1.2 s2 3.4 s3 5.6 s4 7.8 s5 9.0 /; Scalar a,scenToPick; scenToPick = uniformInt(1,card(scen)); a = sum(scen$(ord(scen)=scenToPick),Dataset(scen)); Display scenToPick, a; scenToPick = uniformInt(1,card(scen)); a = sum...
by Lutz
6 months ago
Forum: Syntax
Topic: Stochastic Linear Programming - Multiple Randomness
Replies: 5
Views: 424

Re: Stochastic Linear Programming - Multiple Randomness

Now my question is, what actually does GAMS EMS solver solve, a mean-value problem? a deterministic equivalent problem? a wait-and-see problem? I am not really sure how EMS dictionary solve, especially for continuous distribution. Does EMS do sampling automatically if I call a dictionary to deal wi...
by Lutz
6 months ago
Forum: Modeling
Topic: Random sampling problem of Stochastic Programming
Replies: 2
Views: 279

Re: Random sampling problem of Stochastic Programming

Hi, There are some smaller issues in your model (e.g. "Option emp=lindo;" should be set before your solve statement and not afterwards), but I could not reproduce that "sample" is an unknown keyword. Maybe the GAMS version you are using is too old? "Sample" as keyword was introduced with GAMS 24.1.1...
by Lutz
6 months ago
Forum: Syntax
Topic: Stochastic Linear Programming - Multiple Randomness
Replies: 5
Views: 424

Re: Stochastic Linear Programming - Multiple Randomness

Gabriel, There are two problems which I found in your model: The first one is an easy one, probably just a typo: In the emp.info file you defined "randvar d2 ..." twice. I guess the second one should actually be "randvar d3 ...". The second problems seems to be deeper: You say that your model should...
by Lutz
6 months ago
Forum: Announcements
Topic: GAMS Distribution 25.1.0 (Beta Version) Announcement
Replies: 1
Views: 302

GAMS Distribution 25.1.0 (Beta Version) Announcement

Hi GAMS Users, We would like to announce the availability of the GAMS Release 25.1.0 (Beta Version). This release contains the first public beta version of GAMS Studio - a completely new integrated development environment for GAMS. Please consult the beta release notes for details about GAMS Studio,...
by Lutz
7 months ago
Forum: Syntax
Topic: Stochastic Programming with multiple stochastic parameters
Replies: 2
Views: 348

Re: Stochastic Programming with multiple stochastic parameters

... randvar d(n) discrete 0.25 70 0.5 100 0.25 130 ... Then how could I establsih a multi-randomness model? In my case, I have two variables which both obey the discrete distribution. ... Hi, First to make sure, that I understand what you want to do: You mention two variables which follow the discr...
by Lutz
7 months ago
Forum: Syntax
Topic: The .fx variable attribute: Dumb question
Replies: 1
Views: 361

Re: The .fx variable attribute: Dumb question

Hi, About q1: It is correct, that .fx also sets .l (in contrast to setting .lo and .up separately). About q2: I don't know where exactly you found the things you quoted here from the documentation, but I just searched for the fx attribute and found this (https://www.gams.com/latest/docs/UG_Variables...
by Lutz
7 months ago
Forum: Modeling
Topic: Joint random variable sampling not work?
Replies: 1
Views: 340

Re: Joint random variable sampling not work?

Hi,

Could you post your model? Then it would be easier to help.

Best regards,
Lutz