Re: permutation

[Sundar Dorai-Raj <sundar.dorai-raj@pdf.com>]

Reyderman, Larisa wrote on 4/14/2005 3:54 PM:
> Dear All,
>
> I have a seemingly easy question.  I need to create a matrix consisting of
> all possible permutations of the following vector:
>
> 0.5  1.0  1.5  2.0  3.0  4.0  5.0  6.0  8.0 10.0 12.0 16.0
>
> I know that "sample" function with (replace=F) will generate a permutation,
> however, I need all possible permutations.
>
> Thank you for your help.
>
> Larisa
If you have access to R then there's a package called gtools (part of 
the gregmisc bundle) that has a function to do this. I'm sure it's 
easily ported to S-PLUS. However, with your problem 12 values gives 12! 
possible permutations, or nearly 480 million possibilities. Are you sure 
you want *all* permutations? If so, consider doing this in C.
--sundar