Re: Combinations
- To: mathgroup at smc.vnet.net
- Subject: [mg30788] Re: Combinations
- From: macJL <macJL at arrakis.es>
- Date: Wed, 19 Sep 2001 00:16:27 -0400 (EDT)
- References: <9nh2jh$ml$1@smc.vnet.net>
- Sender: owner-wri-mathgroup at wolfram.com
Combinations: C[n_,m_]:=Binomial[n,m] (n>m>=0, n,m: Integers) Permutations: P[n_,m_]:=Binomial[n,m]*Factorial[m] (for n>m>=0, n,m: Integers) In article <9nh2jh$ml$1 at smc.vnet.net>, Dana <ng_only at hotmail.com> wrote: >Hello. I have Mathematica 4.1 > >In a Program like Excel, or a hand-held calculator, one can return the >number of combinations and permutations. > >However, I can not find an equivalent function in Mathematica. >For example, Permutations[ ] returns a long list of all the "Actual" >permutations. >I am looking for just the final number. >If there is one, could you include 'how' you found it. I have looked >everywhere. >I know DiscreteMath`Combinatorica` has some stuff in it, but the Help system >appears not to explain many of them. > >I can write a custom function, but I am curious to find out if this function >is built in to Mathematica. > >I hope the answer is not to take the Length[ ] of a rather long list. > >TIA. Dana > >(I posted this question a month ago, but it never showed up in the >newsgroup, or in the archives. >I hope I am not doing something wrong.)