Re: bug in Mathematica?
- To: mathgroup at smc.vnet.net
- Subject: [mg122674] Re: bug in Mathematica?
- From: Andrzej Kozlowski <akoz at mimuw.edu.pl>
- Date: Sat, 5 Nov 2011 04:48:11 -0500 (EST)
- Delivered-to: l-mathgroup@mail-archive0.wolfram.com
- References: <201111041103.GAA29326@smc.vnet.net>
This is clearly a rather nasty bug. To see it more clearly:
f[m_, k_] := Product[Binomial[m, j], {j, 1, k}]
For numerical m and k we get the correct answer:
f[10, 2]
450
For symbolic n and m we get nonsense:
In[7]:=
f[m, n] /. {m -> 10, n -> 2}
During evaluation of In[7]:= Power::infy:Infinite expression 1/0^2 encountered. >>
During evaluation of In[7]:= Infinity::indet:Indeterminate expression 0 ComplexInfinity encountered. >>
Out[7]=
Indeterminate
In particular:
f[m, m - 1]
0
f[m, m + 1]
(I^(m*(m + 5))*m*(m*BarnesG[1 - m])^m*BarnesG[2 - m]^(-m - 1))/
BarnesG[m + 3]
which is also nonsense, since
Binomial[n, n + 1]
0
Andrzej Kozlowski
On 4 Nov 2011, at 12:03, Hansruedi Widmer wrote:
> Hi Everyone
>
>
> The code
>
> Sum[Binomial[m, j], {j, 1, m - 1}]
>
> produces the correct value -2+2^m.
>
>
> But the code
>
> Product[Binomial[m, j], {j, 1, m - 1}]
>
> creates the wrong value of zero. Does anyone have an explanation for why
> this is happening?
>
>
> Thanks and best regards
>
> Hansrued Widmer
>
>
>
>
- References:
- bug in Mathematica?
- From: "Hansruedi Widmer" <widmer@baden.ch>
- bug in Mathematica?