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Named Patterns in Switch

• To: mathgroup at smc.vnet.net
• Subject: [mg48945] Named Patterns in Switch
• From: "David Park" <djmp at earthlink.net>
• Date: Thu, 24 Jun 2004 05:36:29 -0400 (EDT)
• Sender: owner-wri-mathgroup at wolfram.com

Dear MathGroup,

Here is an attempted routine using Switch that does not work.

foo[expr_] :=
 Switch[expr,
        (a_.)*x^(n_), a,
        (a_.)*y^(n_), n]

foo[3*x^3]
a			(I was hoping for 3)


Switch uses patterns, but any named patterns are useless. So the a in the third argument in Switch has nothing to do with the a_. in the second argument.

Is there some Mathematica construction that will test successive patterns with names, do a calculation with the first match and use the names in the patterns?

David Park
djmp at earthlink.net
http://home.earthlink.net/~djmp/ 

• Follow-Ups:
  • Re: Named Patterns in Switch
    • From: Yasvir Tesiram <tesiramy@omrf.ouhsc.edu>
  • Re: Named Patterns in Switch
    • From: Andrzej Kozlowski <akoz@mimuw.edu.pl>
  • Re: Named Patterns in Switch
    • From: DrBob <drbob@bigfoot.com>