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Re: Mathematica cannot simplify a product of UnitStep functions

• To: mathgroup at smc.vnet.net
• Subject: [mg55148] Re: [mg55118] Mathematica cannot simplify a product of UnitStep functions
• From: yehuda ben-shimol <bsyehuda at gmail.com>
• Date: Mon, 14 Mar 2005 03:43:49 -0500 (EST)
• References: <200503130957.EAA09928@smc.vnet.net>
• Reply-to: yehuda ben-shimol <bsyehuda at gmail.com>
• Sender: owner-wri-mathgroup at wolfram.com

It is working correctly under 5.1 (Win XP)
yehuda


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
> 
>

• References:
  • Mathematica cannot simplify a product of UnitStep functions
    • From: Alain Cochard <alain@geophysik.uni-muenchen.de>