GAMS World Forum

Hi Patrick, aa and bb are sets (or aliases). Set elements are strings (even if you use numbers). Hence, something like Occ_Fac(k,x+aa-1,y+bb-1) is not possible. Maybe the ord operator or the .val attribute is useful for you. In general, helping becomes easier if you share code that can be executed t...

For example, the solver might run into numerical difficulties.

Best,
Fred

Hi, you could use a big M formulation and change your model as follows: $eolcom // set y year /0*10/ parameter a(y) / 1 -5.5 2 -16.5 3 -20.5 4*10 30.5 / display a; scalar bigM /100/; free variable b obj fake objective; negative variable c ; positive variable d ; binary variable e ; equation eq1 eq2 ...

Hi,

The documentation on subsets might be helpful.

Best,
Fred

If I understand correctly what you try to do, you could just write

Code: Select all

[...]
if(ord(it)=1,
  R.fx('s1')=4;
  Q.fx('s1')=4;
else
  R.fx('s1') = R.l('s3');
  Q.fx('s1') = R.l('s3');
);

Solve rolling using LP minimizing cost;
[...]

I hope this helps!

Fred

Hi, GDXXRW is a Windows only tool (see tools/platform matrix ). The reason is that the Excel program on the Mac lacks the OLE interface, so the approach gdxxrw uses under windows is not possible on Mac. Workarounds could be to create the GDX under Windows and bring it to the MAC or to export Excel d...

Hi, It is hard to guess why you experience problems with your code without being able to reproduce such problems. In general, if you solve a MIP to optimality (i.e. you have to set the termination criterion accordingly, e.g. optcr=0 ), the objective function value should be the same. The solution ca...

Hi, The parameters you are trying to load have domain sets. You need to make sure that those domain sets are known. There are different ways how to do that. I don't know where data of the sets INTERVAL, GEN, MG_GEN comes from in your case. If those sets can be defined through the same gdx files, you...

Hi, You can see in the column listing column listing that R(s1) and Q(s1) are fixed to 4 for the first iteration which seems to be intended. For subsequent iterations you do if (ord(it)>1, R.fx(s)$(ord(s)=1)=R.l(s)$(ord(s)=ch and ord(it)=ord(it)-1); Q.fx(s)$(ord(s)=1)=Q.l(s)$(ord(s)=ch and ord(it)=o...

Hi,

What about

Code: Select all

set p      plants / Oil, gas, coal, nuclear /
    p1(p)         / Oil, gas, coal /
    p2(p)         / nuclear /
;

When you need to refer to all of them, use p.
When you need to refer to Oil, gas, coal, use p1.
When you need to refer to nuclear, use p2.

Fred

GAMS World Forum

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