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