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 > > > > >