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RE: next question - find some element of a set
From: |
Meketon, Marc |
Subject: |
RE: next question - find some element of a set |
Date: |
Thu, 12 Dec 2019 15:19:44 +0000 |
Here is more clarification. I have a set S and an array cost[]. I wanted
to get a cost -- any cost -- that is found in the array cost. I didn't want
to have to specify in the data section a sample element of S, I just wanted to
use GMPL to find one. In the example below, I want to find SOME_ELEMENT_IN_S
as an index to the array cost[].
set S;
param cost{S};
param some_valid_cost := cost[SOME_ELEMENT_IN_S];
data;
param : S : cost :=
A 100
B 105
C 198
;
-----Original Message-----
From: Help-glpk <help-glpk-bounces+marc.meketon=address@hidden> On Behalf Of
Mate Hegyhati
Sent: Thursday, December 12, 2019 2:29 AM
To: address@hidden
Subject: Re: next question - find some element of a set
Hi!
I'm not exactly sure, what you would like to do, but you could just say, but
maybe this answers your question:
set sports;
param favorite symbolic in sports;
var train{sports} >=0;
s.t. foobar: train[favorite] >=2;
minimize work: sum{f in sports} train[f];
data;
set sports := running cycling swimming;
param favorite := 'running';
end;
So put ' around the name for a symbolic parameter, and also don't put comma
between set elements.
I hope this helped. If not, please clarify your situation.
All the best,
Mate
> set := A, B, C;
>
> param some_element_in_set, symbolic := ?????;
>
> The closest I saw was in this old help-glpk email:
> https://lists.gnu.org/archive/html/help-glpk/2006-11/msg00059.html
>
> Which says:
>
> set S;
>
> param ref{i in 1..card(S)}, symbolic, in S;
>
> # ref[i] refers to i-th element of S;
>
> param a{S};
>
> ... a[ref[i]] ... # means a[i-th element of S]
>
> But I cannot get this to work. If I could get it to work, then I
> would do something like: param some_element_in_set := ref[1];
>
> BTW, I’m still hoping that someone will help solve how to work the
> sudoku_excel.mod example in the ‘examples\sql’ directory of the GLPK
> directory under Windows 10 64bit. I still cannot get that to work.
>
> -Marc
>