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Re: Style Question: The Functional Way

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  • Subject: [mg115809] Re: Style Question: The Functional Way
  • From: Oliver Ruebenkoenig <ruebenko at>
  • Date: Fri, 21 Jan 2011 04:32:42 -0500 (EST)

On Thu, 20 Jan 2011, Just A Stranger wrote:

> Hello,
> So I'm trying to learn how to do things the functional way. As an exercise
> I'm trying to program a simple economics related table that gives revenue,
> marginal revenue, etc given a demand schedule (2 lists of numbers
> representing quantity and price respectively). A simple task in a
> spreadsheet.
> The point is that I need a list of the differences in the given lists, from
> which I will be using to get marginal values (derivatives). I'll call it,
> say, DeltaList, and I was wondering if this would be a proper "functional"
> way to go about the task:
> In[0]: DeltaList[L_] := Subtract @@@ Reverse /@ Partition[L, 2, 1]
> (DelatList: list -> list)

here is another way

data = RandomReal[{-1, 1}, 100];
DeltaList[data] = Most[RotateLeft[data] - data]


> Basically, it partitions the list into ordered pairs, reverses those ordered
> pairs to prep them for the subsequent Subtract application.
> Is this the right way to think about this (painfully simple) problem in a
> functional way?
> Thank you. All of you have been most helpful in the past.

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