Services & Resources / Wolfram Forums
-----
 /
MathGroup Archive
2003
*January
*February
*March
*April
*May
*June
*July
*August
*September
*October
*November
*December
*Archive Index
*Ask about this page
*Print this page
*Give us feedback
*Sign up for the Wolfram Insider

MathGroup Archive 2003

[Date Index] [Thread Index] [Author Index]

Search the Archive

Re: Pattern matches only when named

  • To: mathgroup at smc.vnet.net
  • Subject: [mg43878] Re: Pattern matches only when named
  • From: Jens-Peer Kuska <kuska at informatik.uni-leipzig.de>
  • Date: Fri, 10 Oct 2003 03:05:47 -0400 (EDT)
  • Organization: Universitaet Leipzig
  • References: <bm2ugv$6so$1@smc.vnet.net>
  • Reply-to: kuska at informatik.uni-leipzig.de
  • Sender: owner-wri-mathgroup at wolfram.com

Hi,

and 
_ + _  is simplifyed to 2 _ and this does not match a
sum. While u_ + _ can not simplifyed and matches your sum.
You must use

f + g /. HoldPattern[ _ + _] -> h

and all works as expected.

Regards
  Jens

Ken Morgan wrote:
> 
> Just a curiosity:
> 
> In[1]:=   f + g /. u_ + _ -> h
> Out[1]:=  h
> 
> but
> 
> In[2]:=   f + g /. _ + _ -> h
> Out[2]:=  f + g
> 
> Why does the pattern match only when one of the Blanks has a name?
> 
> Thanks,
> Ken


  • Prev by Date: Re: 3D Plots
  • Next by Date: Simplifying Exponents
  • Previous by thread: RE: Pattern matches only when named
  • Next by thread: Re: Pattern matches only when named