Re: Factorising polynomials
- To: mathgroup at smc.vnet.net
- Subject: [mg63980] Re: Factorising polynomials
- From: "Scout" <Scout at nodomain.com>
- Date: Thu, 26 Jan 2006 03:43:02 -0500 (EST)
- References: <dr80c0$phj$1@smc.vnet.net>
- Sender: owner-wri-mathgroup at wolfram.com
"Tony King" <mathstutoring at ntlworld.com>
>I am trying to find the number of irreducible polynomials over the integers
> in the factorisation of x^n+1
>
> I used the following code
>
> data = Factor[x^# + 1] & /@ Range[6]
>
> Followed by
>
> Table[Length[data[[k]]], {k, 1, 6}]
>
> And Mathematica returned {2,2,2,2,2,2}, one assumes because it was
> counting
> terms such as 1+x as 2 terms. However, when the number of factors exceeds
> 1,
> Mathematica returns them as a list and counts them correctly. The output
> that I was looking for should have been {1,1,2,1,2,2}.
>
> Does anyone have any ideas how I might modify the above code so that it
> returns the correct number of terms
>
> Many thanks
>
> Tony
>
Hi Tony,
maybe this could help you:
(Length /@ (FactorList /@ data) - 1)
~Scout~