Re: 15! permutations
- To: mathgroup at smc.vnet.net
- Subject: [mg108649] Re: 15! permutations
- From: Nicola Mingotti <n-no-mingotti at g-spam-mail.com>
- Date: Fri, 26 Mar 2010 05:35:23 -0500 (EST)
- References: <hofgdo$fdg$1@smc.vnet.net>
On 2010-03-25 12:11:52 +0100, bn77 said: > Hi, > > I'm trying to write a program in mathematica that compares roughly > (15!)^2 / 2 pairs of permutations of length 15. Can mathematica do this > in a reasonable time? Any experience of this sort? > > TIA, > bn77 The number of permutations is then : N[((15!)^2)/2] => 8.55006*10^23 Supposing you can compare 10^9 objects per second you would need 10^4 seconds that is 3.171 milion years according to Wolfram Alpha conversion. So, no ! If you really need to cycle through all these objects it's impossible. Brute force here fails, you need to find a smarter way to solve it. bye Nicola.