Re: Inconsistent behavior?

*To*: mathgroup at smc.vnet.net*Subject*: [mg87285] Re: [mg87243] Inconsistent behavior?*From*: Andrzej Kozlowski <akoz at mimuw.edu.pl>*Date*: Sun, 6 Apr 2008 06:45:16 -0400 (EDT)*References*: <200804050923.EAA12082@smc.vnet.net>

Binomial[n,r] is automatically expanded only for small values of r. For large ones you need to use FunctionExpand: FunctionExpand[Binomial[n, 11]] ((n - 10)*(n - 9)*(n - 8)*(n - 7)*(n - 6)*(n - 5)* (n - 4)*(n - 3)*(n - 2)*(n - 1)*n)/39916800 (The distinction between "small" and "large" numbers is a little problematic logically, since one can "prove" by induction that all positive integers are small, assuming that 1 is small and "n is small -> (n+1) is small", but as a matter of practice it seems a sensible idea.) Andrzej Kozlowski On 5 Apr 2008, at 10:23, angela wrote: > Binomial[n,4] yields > 1/24 (-3+n) (-2+n) (-1+n) n > > Binomial[n,5] yields > 1/120 (-4+n) (-3+n) (-2+n) (-1+n) n > > Binomial[n,6] yields > Binomial[n,6] > > Binomial[n,7] yields > Binomial[n,7] > > Is some setting doing this. > > Thanks; > Angela >

**References**:**Inconsistent behavior?***From:*angela <mpopyft@lycos.com>