## Search found 201 matches

- 7 months ago
- Forum: Modeling
- Topic: Increasing ‘reslim’ but weaker result in a mip solver
- Replies:
**5** - Views:
**487**

### Re: Increasing ‘reslim’ but weaker result in a mip solver

One potential explanation could be that you suffer from non-deterministic behavior when cplex hits the time limit. When you use time limits, the solving process becomes non-deterministic close to the end of the time limit. Eventually, Cplex does "something smart" close to the end with reslim=360 whi...

- 7 months ago
- Forum: Modeling
- Topic: Increasing ‘reslim’ but weaker result in a mip solver
- Replies:
**5** - Views:
**487**

### Re: Increasing ‘reslim’ but weaker result in a mip solver

Hi,

What about the log files and files required for reproduction?

Fred

What about the log files and files required for reproduction?

Fred

- 7 months ago
- Forum: Modeling
- Topic: Increasing ‘reslim’ but weaker result in a mip solver
- Replies:
**5** - Views:
**487**

### Re: Increasing ‘reslim’ but weaker result in a mip solver

Hi, Assuming that you solve the exact same problem on the exact same hardware with the exact same software and that there are no other computationally expensive jobs running simultaneously, increasing reslim should not lead to a worse solution. You don't say whether you minimze or maximize but from ...

- 8 months ago
- Forum: Modeling
- Topic: GAMS/convert solver
- Replies:
**2** - Views:
**738**

### Re: GAMS/convert solver

Hi, MPS is a file format for linear problems: https://en.wikipedia.org/wiki/MPS_(format) If you look into the resulting mps file, you should see hints like * Cannot handle NLP [...] * Cannot handle nonlinear equations, nonlinear part ignored. * Cannot handle nonlinear equations, nonlinear part ignor...

- 8 months ago
- Forum: Syntax
- Topic: Dynamic set allocation with binary variable
- Replies:
**9** - Views:
**1415**

### Re: Dynamic set allocation with binary variable

Hi, you are absolutely right. I edited my post accordingly.

Fred

Fred

- 8 months ago
- Forum: Syntax
- Topic: Dynamic set allocation with binary variable
- Replies:
**9** - Views:
**1415**

### Re: Dynamic set allocation with binary variable

Hi, So you want a constraint that calculates the sum of all distances w(p1,p2) between pixels p1 and p2 on which a house h is built? I think a straightforward (quadratic) formulation could look as follows: equation houseDistNL; positive variable distNL; alias(h,h1,h2), (p,p1,p2); houseDistNL.. distN...

- 8 months ago
- Forum: Syntax
- Topic: Dynamic set allocation with binary variable
- Replies:
**9** - Views:
**1415**

### Re: Dynamic set allocation with binary variable

Hi, The dynamic set won't help if you need that during the solution process. I guess there are model formulations that do what you want but it is a bit tedious to guess how this could fit into an unknown model. If you share your model and explain where you are struggling to find the right formulatio...

- 8 months ago
- Forum: Syntax
- Topic: Dynamic set allocation with binary variable
- Replies:
**9** - Views:
**1415**

### Re: Dynamic set allocation with binary variable

Hi, Your syntax is almost corrrect. It only misses the level attribute of the variable (https://www.gams.com/latest/docs/UG_Variables.html#UG_Variables_VariableAttributes) and it seem that h is a set elemnt which means it should be quoted. Also, I suggest not to test for equality (due to tolerances ...

- 8 months ago
- Forum: Modeling
- Topic: Problem with creating a constraint for a minimum amount of consecutive days
- Replies:
**1** - Views:
**290**

### Re: Problem with creating a constraint for a minimum amount of consecutive days

Hi, I think the following example should do the trick. binary variable y(i,l) 'worker i works on day l'; variable start(i,l) 'value of 1 indicates that worker i starts to work on day l'; equation defStart(i,l) minconsec(i,l); defStart(i,l).. start(i,l) =e= y(i,l) - y(i,l-1); minconsec(i,l)$(ord(l)>1...

- 9 months ago
- Forum: Syntax
- Topic: Error 66 even when all symbols are defined and assigned... help!
- Replies:
**2** - Views:
**481**

### Re: Error 66 even when all symbols are defined and assigned... help!

Hi, If you look into the listing file, the first error you get is **** $66,256,299 UNEXPECTED END OF FILE (1) **** 3 ERROR(S) 0 WARNING(S) After adding a semicolon after the solve statement yo get 79414 solve MEPI using mip minimizing of; **** $66,256 **** LINE 251 INPUT C:\Users\user\Documents\supp...