Re: sum of binomials .. bug ?
- To: mathgroup at smc.vnet.net
- Subject: [mg70490] Re: sum of binomials .. bug ?
- From: "ben" <benjamin.friedrich at gmail.com>
- Date: Wed, 18 Oct 2006 04:16:12 -0400 (EDT)
- References: <eh20si$2ms$1@smc.vnet.net>
Dear Yann,
got the same bug on linux,
even
f[k_] := Sum[Binomial[2 - k, i], {i, 0, 1 - k}]
x = 1; f[x] Clear[x]; f[x] /. x -> 1
gives wrong results.
Bye
Ben
yann_che2 at yahoo.fr schrieb:
> Hi everyone,
>
> on Mathematica 5.2 (mac os x), experimenting sums of binomials, i tried
> the following:
>
> In[6]:= f[k_] := Sum[Binomial[21 - k, i], {i, 0, 10 - k}]
> In[7]:= x = 3; f[x]
> Out[7]:= 63004
> In[8]:= Clear[x] ; f[x] /. x -> 3
> Out[8]:= 262144
> In[9]:= Clear[x] ; f[x]
> Out[9]:= 2^(21-x)
>
>
> does anyone know why Out[7] and Out[8] give different results ? do you
> think it is a bug ? i searched everywhere in the forums but couldn't
> find anything that helped.
> do you have a clue ?
>
> yann