Deleting Selective DownValues
- To: mathgroup at smc.vnet.net
- Subject: [mg63984] Deleting Selective DownValues
- From: "David Park" <djmp at earthlink.net>
- Date: Thu, 26 Jan 2006 03:43:10 -0500 (EST)
- Sender: owner-wri-mathgroup at wolfram.com
Dear MathGroup,
Suppose I have established the following definitions for f, but not necessarily in the given order.
Clear[f]
f[x_, y_, z_] := x y z
f[a_, b_] := a b
f[x_] := x
DownValues[f]
{HoldPattern[f[x_, y_, z_]] :> x y z, HoldPattern[f[a_, b_]] :> a b,
HoldPattern[f[x_]] :> x}
Now I would like to delete the f definition that has a given number of arguments, say f[a_,b_] with 2 arguments. So I need a routine:
deleteDownValue[label_Symbol,numberOfArgs_Integer?Positive]:= ???
which would reset DownValues[label] to eliminate any definition with numberOfArgs arguments.
I have trouble with doing the matches and evaluation sequences. Can anyone help with this? Many thanks in advance.
David Park
djmp at earthlink.net
http://home.earthlink.net/~djmp/
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- From: Andrzej Kozlowski <akoz@mimuw.edu.pl>
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