Dear Biswajit,
On Mon, Aug 18, 2014 at 09:15:26AM -0700, Biswajit Ransingh wrote:
> W=WeylGroup(['E',8])
>
> R = RootSystem(['E',8]).root_lattice()
>
> alpha = R.simple_roots();alpha
>
> [w for w in W if w.action(alpha[1])==(alpha[1]+alpha[2])]
>
> Output shows : gap: cannot extend the workspace any more!
Your e-mail could be a bit more explicit about the end-goals :-) But
it contains the most important information: code to reproduce the
problem step by step!
In this case, the message is rather explicit: this calculation has
eaten up all of gap's memory. The natural guess is that GAP is storing
the list of all the elements of E_8, which is big.
The questions to explore are:
- Do you have a way to achieve the same calculation without having to
iterate through all the of E_8. Here we are essentially computing a
stabilizer for which there exists much better algorithms.
- Can GAP iterate through the elements of a finite matrix group (at
this point this is all GAP know about the group) without storing
them all in memory.
- If yes, can Sage's iterator over the elements of a Weyl group be
fixed to make it call GAP's iterator properly.
Cheers,
Nicolas
--
Nicolas M. Thiéry "Isil" <nthi...@users.sf.net>
http://Nicolas.Thiery.name/
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