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MathGroup Archive 2003

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Re: nth differences

  • To: mathgroup at smc.vnet.net
  • Subject: [mg39877] Re: nth differences
  • From: Daniel Reeves <dreeves at umich.edu>
  • Date: Sun, 9 Mar 2003 05:30:22 -0500 (EST)
  • Organization: University of Michigan Engineering
  • References: <b4c9lo$nqg$1@smc.vnet.net>
  • Sender: owner-wri-mathgroup at wolfram.com

difs[x_] := (#2-#1&) @@@ Partition[x, 2, 1]

For the nth differences, you can do 
  Nest[difs, x, n]

--- \/   FROM Zachary Turner AT 03.03.08 08:29 (Today)   \/ ---

> 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

-- 
Daniel Reeves  --  http://ai.eecs.umich.edu/people/dreeves/      

Mathematicians do it continuously and discretely.
  -- bumper sticker by Robert L Dawes



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