Re: [Help-glpk] Subset

[glpk xypron]

Hello Kasper,

> but if it's just the set containing the kth member of S, couldn't you
> just say S[k] then instead of making a new set?
unfortunately not, S cannot be accessed by an index.

Furthermore there is no function to return a single element of a set.

If you look at the definition of ELEMSET in src/glpmpl.h you will
see that elemental sets are stored as linked list. Hence access
via a numeric index would cost O(n) time which is not
efficient.

In the follwing thread I suggested to provide a syntax
extension 
http://lists.gnu.org/archive/html/help-glpk/2008-12/msg00109.html

Best regards

Xypron

-------- Original-Nachricht --------
> Datum: Tue, 18 Oct 2011 11:08:59 +0200
> Betreff: Re: [Help-glpk] Subset

> Hi Xypron
> Thanks for the reply, it looks like something I can use.
> I have a question though. I don't understand the set L (Set containing the
> kth member of S), maybe it's because I don't understand the setof
> operation,
> but if it's just the set containing the kth member of S, couldn't you just
> say S[k] then instead of making a new set?
> I understand it like if I were to say L[2] I would get 'B' in the example
> you sent.
> 
> Regards,
> Kasper

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