MathGroup Archive: November 2006 [00453]

[Date Index] [Thread Index] [Author Index]

List difference using patterns and substitutions.

To: mathgroup at smc.vnet.net
Subject: [mg71306] List difference using patterns and substitutions.
From: "Nacho" <ncc1701zzz at gmail.com>
Date: Tue, 14 Nov 2006 05:06:25 -0500 (EST)

Hello.

I'm trying to figure how can I build a difference list from another
using only patterns and rule substitutions.

The idea is to get from a list, another, one element shorter, where
each value is the substraction of two consecutive elements in the
original list, that is, from {1,2,3,5,5} get {1,1,2,0}.

I've been thinking about it for a while, and I know several methods
using a more traditional programming style (with For, for example), but
I have no idea if it is possible to make it simple and fast with rule
substitutions.

Any idea? 

Thanks in advance.

Follow-Ups:
- Re: List difference using patterns and substitutions.
  - From: gardyloo <gardyloo@mail.wsu.edu>
- Re: List difference using patterns and substitutions.
  - From: János <janos.lobb@yale.edu>
- Re: List difference using patterns and substitutions.
  - From: Andrzej Kozlowski <akoz@mimuw.edu.pl>
- Re: List difference using patterns and substitutions.
  - From: Sseziwa Mukasa <mukasa@jeol.com>

Prev by Date: Re: Possible bug concerning a limit computation

Next by Date: Re: finding the (v,w) weighted degree of a polynomial

Previous by thread: RE: Re: Re: Re: Arithmetic Puzzle (so simple it's hard)

Next by thread: Re: List difference using patterns and substitutions.