Search found 639 matches

by Renger
3 years ago
Forum: Modeling
Topic: Linearisation of Bilinear Terms Using McCormick Envelopes
Replies: 1
Views: 2596

Re: Linearisation of Bilinear Terms Using McCormick Envelopes

Hi If you sum over f in your equations, the equation can't have the index f in it. z(n,i,f) =E= q*sum(f, stream(n,i, f)); Relax1(n,i,f).. z(n,i,f) =E= q*sum(f, stream(n,i, f)) should then be variable z(n,i) equations eq3(n,i), relax1(n,i); eq3.. z(n,i) =E= q*sum(f, stream(n,i, f)); Relax1(n,i).. z(n...
by Renger
3 years ago
Forum: Syntax
Topic: SET or PARAMETER
Replies: 2
Views: 3212

Re: SET or PARAMETER

Hi
It looks like a newer feature as it runs fine with Gams 30.2.
Cheers
Renger
by Renger
3 years ago
Forum: Syntax
Topic: Set definition variable number of elements
Replies: 2
Views: 2098

Re: Set definition variable number of elements

Hi Nikou

Just have a look here.

Cheers
Renger
by Renger
3 years ago
Forum: Syntax
Topic: how to write the row of sets
Replies: 11
Views: 5910

Re: remove the duplicate item

Hi
Use the same logic for i and k for b(j,i,k):

Code: Select all

b(j,i,k)$(ord(i) ne ord(k) .....)
Cheers
Renger
by Renger
3 years ago
Forum: Syntax
Topic: looping solve statement over time set
Replies: 4
Views: 5516

Re: looping solve statement over time set

Hi You could introduce two positive variables Rn, Qn and add the following equations: positive variables Rn Reserve in next period, Qn ....; eqR.. Rn =E= R + beta_c_E*(x2 + x6) - beta_d_E * x9; eqQ.. Qn =E= Q + beta_c_T*(QchST + sum(i,k1(i) * x11(i)))- sum(i, beta_d_T*x12(i)); After the solve, you a...
by Renger
3 years ago
Forum: Syntax
Topic: looping solve statement over time set
Replies: 4
Views: 5516

Re: looping solve statement over time set

Hi It looks like you want to model a recursive model, where the values of R and Q for the next period are defined using the actual period. You have to do the following to be able to run over t. You keep your original parameters but define new parameters for the model without a time index. E.g. you r...
by Renger
3 years ago
Forum: Modeling
Topic: Creating diferent instances with changing parameters
Replies: 1
Views: 1889

Re: Creating diferent instances with changing parameters

Hi Sorry for being not clear enough. If your data looks like this *HOMO hc(k) euro per unit /k0 0, k1 0.05,k2 0.05,k3 0.05/ pq(k) kW /k0 1, k1 162.72, k2 162.72, k3 162.72/ *TO HETERO *hc(k) euro per unit /k0 0, k1 0.025,k2 0.05,k3 0.075/ *pq(k) kW /k0 1, k1 81.36, k2 162.72, k3 244.08/ Then, I woul...
by Renger
3 years ago
Forum: Modeling
Topic: Error 149 - Uncontrolled Set Entered As Constant
Replies: 1
Views: 1558

Re: Error 149 - Uncontrolled Set Entered As Constant

Hi
I am not sure, if this is what you want to achieve:

Code: Select all

alias(b,bb);
 eq(b,c).. SUM((a,bb), f1(a,bb,c))  =e=  SUM (a, f2(a,b))
Cheers
Renger
by Renger
3 years ago
Forum: Modeling
Topic: How do I set the values of a multidimensional parameter step by step (to implement a cutting plane approach)?
Replies: 1
Views: 1505

Re: How do I set the values of a multidimensional parameter step by step (to implement a cutting plane approach)?

Hi You could define a set i for the number of iterations. ALthough you don't know the maximum number of iterations, you can set it to a very high number, e.g.: set i Iterations /1*1000/ Then you can use your assignment as follows: parameter itnr Iteration number /0/; while(... itnr = itnr + 1; .... ...
by Renger
3 years ago
Forum: Modeling
Topic: should I use a loop in calculate standard deviation
Replies: 1
Views: 1626

Re: should I use a loop in calculate standard deviation

Hi Sandy
See my answer to your other post regarding ord(k-1).
To sum, you should sum over an alias as the equation is defined over k.

Code: Select all

alias(k,kk)
sum(kk, ....)
CHeers
Renger