Services & Resources / Wolfram Forums
-----
 /
MathGroup Archive
2005
*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 2005

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

Search the Archive

Re: Mathematica cannot simplify a product of UnitStep functions

  • To: mathgroup at smc.vnet.net
  • Subject: [mg55141] Re: [mg55118] Mathematica cannot simplify a product of UnitStep functions
  • From: "Christoph Lhotka" <lhotka at astro.univie.ac.at>
  • Date: Mon, 14 Mar 2005 03:43:40 -0500 (EST)
  • Sender: owner-wri-mathgroup at wolfram.com

Hi, on version 5.1 it works...

In[..]:=Simplify[{e1, e2, e1*e2}, x < y < z]
Out[..]:= {0, 0, 0}

with kind regards...


On Sun, 13 Mar 2005 04:57:37 -0500 (EST)
 Alain Cochard <alain at geophysik.uni-muenchen.de> wrote:
> Consider the following:
> 
>     Mathematica 4.0 for Linux
>     Copyright 1988-1999 Wolfram Research, Inc.
>      -- Motif graphics initialized -- 
> 
>     In[1]:= e1=UnitStep[x-y]; e2=UnitStep[x-z]; 
> 
>     In[2]:= FullSimplify[{e1,e2,e1*e2},x<y<z]
> 
>     Out[2]= {0, 0, UnitStep[x - y, x - z]}
> 
> I find it strange that it cannot simplify the product to 0.  Is there
> something mathematically profound here, implying that the true result
> is indeed not 0?? (At least I hope it's not something trivial!)
> Assuming the answer is no, is there a smarter/more elegant way to
> perform the simplification than the workaround I found, which is to
> simplify each term and multiply them.
> 
> Thanks in advance.
> AC
> 
> 


-- Christoph Lhotka --
University of Vienna
Institute for Astronomy
Tuerkenschanzstr. 17 
1180 Vienna, Austria
fon. +43.1.4277.518.41
mail. lhotka at astro.univie.ac.at


  • Prev by Date: Re: Plotting a super ellipse
  • Next by Date: Re: How to use "Solve" to get only real number solutions?
  • Previous by thread: Re: Mathematica cannot simplify a product of UnitStep functions
  • Next by thread: Re: Mathematica cannot simplify a product of UnitStep functions