Re: nth differences
- To: mathgroup at smc.vnet.net
- Subject: [mg39854] Re: [mg39852] nth differences
- From: Andrzej Kozlowski <akoz at mimuw.edu.pl>
- Date: Sun, 9 Mar 2003 05:26:25 -0500 (EST)
- Sender: owner-wri-mathgroup at wolfram.com
Here is one way:
f[l_List,n_Integer?Positive]:=Nest[ListConvolve[{1,-1},#]&,l,n]
l={1,2,5,7,8,9};
f[l,1]
{1,3,2,1,1}
f[l,2]
{2,-1,-1,0}
In[5]:=
f[l,3]
{-3,0,1}
Andrzej Kozlowski
Yokohama, Japan
http://www.mimuw.edu.pl/~akoz/
http://platon.c.u-tokyo.ac.jp/andrzej/
On Saturday, March 8, 2003, at 04:52 pm, Zachary Turner wrote:
> Say I have a list of k integers and I want to produce a list
> containing the
> first differences? For example, given {1, 2, 5, 7, 8, 9} the first
> differences are {1, 3, 2, 1, 1}, and the second differences are {2,
> -1, -1,
> 0}, the third are {-3, 0, 1}, etc
>
>
>
>
>