[GAP Forum] Choosing random elements from a group

Alexander Hulpke hulpke at math.colostate.edu
Tue May 19 17:57:10 BST 2009

On May 18, 2009, at 5/18/09 10:41, Sandeep Murthy wrote:

> Thank you,
> I'm working on a random search algorithm for
> basic finite non-Abelian groups initially of
> order <= 10^12.
> At what point does the randomness of PseudoRandom()
> degrade compared to Random() for this situation?

As I wrote, this depends on how you represent the groups. Permutation  
groups and pc groups will work fine with `Random', matrix groups might  

My suggestion is to try out both `Random' and `PseudoRandom' on your  
groups (measure the first call separately, as it sets up data  
structures) and see which one performs better in time and memory.
> P. S. I note that the GAP manual describes a RandomList()
> method that is said to be effective for dense lists up
> 2^28 long.
Yes, but then you would need to have already a list of elements of  
your group.


    Alexander Hulpke

-- Colorado State University, Department of Mathematics,
Weber Building, 1874 Campus Delivery, Fort Collins, CO 80523-1874, USA
email: hulpke at math.colostate.edu, Phone: ++1-970-4914288

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