Search found 72 matches

by GabrielYin
5 years ago
Forum: Modeling
Topic: Generate Equation and Column Listing without solving
Replies: 3
Views: 3149

Re: Generate Equation and Column Listing without solving

I'm also interesting in this issue :idea: After checking the documentation, I know that 'solve' statement takes the role of importing and generating all the equations and columns in the predefined model ( https://www.gams.com/latest/docs/UG_GAMSOutput.html#UG_GAMSOutput_TheEquationListing ). Thus an...
by GabrielYin
5 years ago
Forum: Modeling
Topic: HELP! Augmenting master problem with cuts: GAMS does not permit conditional equations
Replies: 5
Views: 3641

Re: HELP! Augmenting master problem with cuts: GAMS does not permit conditional equations

I can't understand. As you say, the 3rd iteration constraint "2.5 <= x <= 8" will be added iff z result in the 2nd iteration is <= 1, but z reaches its optimum 2 in 2nd iteration. So the constraint will not be triggered. You can observe the Equation list in .lst file to check the constrai...
by GabrielYin
5 years ago
Forum: Modeling
Topic: HELP! Augmenting master problem with cuts: GAMS does not permit conditional equations
Replies: 5
Views: 3641

Re: HELP! Augmenting master problem with cuts: GAMS does not permit conditional equations

I can't understand. As you say, the 3rd iteration constraint "2.5 <= x <= 8" will be added iff z result in the 2nd iteration is <= 1, but z reaches its optimum 2 in 2nd iteration. So the constraint will not be triggered. You can observe the Equation list in .lst file to check the constrain...
by GabrielYin
5 years ago
Forum: Modeling
Topic: HELP! Augmenting master problem with cuts: GAMS does not permit conditional equations
Replies: 5
Views: 3641

Re: Augmenting master problem with cuts: GAMS does not permit conditional equations

Hi Anby, First of all, your model is apparently infeasible because you have w <= 22 and w >= 26, which is contradictory. Then the way you add your constraint is weird. But it is still doable in GAMS. I have written the code for you, which shows integer infeasible. Positive Variable x; Integer Variab...
by GabrielYin
5 years ago
Forum: Syntax
Topic: How to keep it compact
Replies: 1
Views: 2461

Re: How to keep it compact

Hi, If you only need to reduce the times you write the term "Parameter", it is very easy: Parameter AH Maximum absolute humidity in hood in g water.(kg dry air)-1 l(c) latent heat for the steam condensation at pr(c) in kJ.kg-1; l(c)= 1.6807*pr(c)*pr(c)-40.975*pr(c)+2270.9 ; AH = 4.8101*exp...
by GabrielYin
5 years ago
Forum: Modeling
Topic: Altering the standard transportation problem
Replies: 3
Views: 3123

Re: Altering the standard transportation problem

Suggest you to post your code which others can run, either using BBcode or attachment :) Then we are more convenient and comprehensive to help you!

Best,
Gabriel
by GabrielYin
5 years ago
Forum: Syntax
Topic: binary variable fixed value for 1 place - solution searched
Replies: 1
Views: 1935

Re: binary variable fixed value for 1 place - solution searched

solution is simple

Code: Select all

ow.fx('w1') = 1;
Suggest you to search relevant documentation first when encountering problem :)

Cheers.
Gabriel
by GabrielYin
5 years ago
Forum: Modeling
Topic: how to use a loop statement into dynamic recursive model?
Replies: 2
Views: 2966

Re: how to use a loop statement into dynamic recursive model?

Hi Rodrigue, To store/use values in each loop, I recommend two alternatives. 1. Define a global parameter to store the value and update it in each iteration. An illustrative example is shown below. Set k /1*100/; Parameter store(n); store(n) = *something initial*; loop(k, param(n) = store(n); * para...
by GabrielYin
5 years ago
Forum: Modeling
Topic: To binary or not to binary...
Replies: 4
Views: 3846

Re: To binary or not to binary...

More precisely, if your variable can ONLY take integer values from 50 to 150, as you stated in the post, then define the variable used by Manassaldi as integer variable like the following. Integer Variable T; T.lo=50; T.up=150; For more definition reference, you can visit the documentation site. htt...
by GabrielYin
5 years ago
Forum: Syntax
Topic: Product between matrices and vector
Replies: 2
Views: 3415

Re: Product between matrices and vector

Hi, Try to use loops. I wrote a simple code for you. set col /1*4/ set row /1*5/ Table matrix(row, col) 1 2 3 4 1 2 3 4 5 2 4 6 2 1 3 9 7 1 0 4 6 7 1 8 5 7 2 3 1 ; Parameter vector(col)/ 1 1 2 1 3 0 4 0 /; Parameter result(row); loop(row, result(row) = sum(col, matrix(row, col) * vector(col)); ); di...