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Re: Operator Definition

In article <3nv9j4$9g8 at>,
Todd Pitts <pitts at mayo.EDU> wrote:
>I would like to define a shift operator similar to the derivative 
>for continuous time that is already built into Mma. i.e. 
>Shift[ how far ][ expression head ] [ variable(s) to which shift should be applied ]
>I would also like to have it enjoy a relationship to something called S sort of
>like D[] and Derivative[][][].  Any ideas on how to define it or where I could
>go to learn how to do it right?  I have the standard Mma reference book by
>Wolfram but haven't (as of yet) been able to extract the proper way to get 
>what I need.
>Thanks in Advance,
>Todd Pitts

You can make definitions like thes in a straightforward way:

    f[a_][b_][c__] := a[b[c]]

    q[r[s, t, u]]

Definitions such as these are called SubValues. SubValues[f] returns a
list of such definitions, much like UpValues or DownValues (except that
it's undocumented):

    {Literal[f[a_][b_][c__]] :> a[b[c]]}

		Dave Wagner
		Principia Consulting
		(303) 786-8371
		princon at

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