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MathGroup Archive 2007

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Re: [TS 28872]--Re:Pattern::nodef: No default setting found for Piecewise in position 2 when length is 2.

  • To: mathgroup at smc.vnet.net
  • Subject: [mg81833] Re: [TS 28872]--Re:Pattern::nodef: No default setting found for Piecewise in position 2 when length is 2.
  • From: "Chris Chiasson" <chris at chiasson.name>
  • Date: Thu, 4 Oct 2007 04:30:27 -0400 (EDT)
  • References: <200710021730.l92HU1Fq025167@localhost.localdomain>

It would come up when people are constructing other expressions from
Piecewise objects or when people are constructing Piecewise objects
from other expressions, especially in any environment where there are
OwnValues or DownValues that must be prevented from executing (which
may or may not occur as part of a pattern or condition test).

I found it when I was writing my second response in this thread,
though I constructed my solution without it:

http://groups.google.com/group/comp.soft-sys.math.mathematica/browse_thread/thread/96490ac6a4d5bf3d/

Lastly, the present behavior doesn't fit in with the rest of the
Mathematica framework.

On Tue, 2 Oct 2007 17:30:01 UT, mathgroup <mathgroup at smc.vnet.net> wrote:
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> This is a response to your email.
> The reply to your question can be found at the bottom of this message.
> Our classification number for this message is: [TS 28872]
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>
> From: "Chris Chiasson" <chris at chiasson.name>
> Date: Wed, 19 Sep 2007 10:01:13 -0500
> Subject: Pattern::nodef: No default setting found for Piecewise in position 2 when length is 2.
> To: mathgroup <mathgroup at smc.vnet.net>,"Wolfram Research Support" <support at wolfram.com>
>
> Is there a good reason why this shouldn't be fixed?
>
> --
> http://chris.chiasson.name/
>
>
> _________________________________________________________________________
> ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
>
> Chris,
>
> I looked at the example you posted to mathgroup:
>
> Hold[Piecewise[{{x,blah}}]]/.HoldPattern[Piecewise]
> [conditions_,default_.]:>f[whatever]+default
>
> It is not clear to me when this would come up.  If you have a "this is
> a problem because ...  or this is a problem when ..." I will add that to
> the report.
>
> Tom Zeller
> Wolfram Research Technical Support
>
>
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-- 
http://chris.chiasson.name/


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