Re: Simplify UnitStep expressions

*To*: mathgroup at smc.vnet.net*Subject*: [mg69205] Re: [mg69195] Simplify UnitStep expressions*From*: Andrzej Kozlowski <akoz at mimuw.edu.pl>*Date*: Fri, 1 Sep 2006 18:41:05 -0400 (EDT)*References*: <200609011041.GAA25645@smc.vnet.net>*Sender*: owner-wri-mathgroup at wolfram.com

On 1 Sep 2006, at 11:41, L. Dwynn Lafleur wrote: > The following is transcribed from a Mathematica 5.2 notebook in > Windows XP: > > In[1]:= Simplify[UnitStep[a-x/b], a-x/b > 0] > Out[1]= 1 > > In[2]:= Simplify[UnitStep[a-Pi/b], a-Pi/b > 0] > Out[2]= UnitStep[a-Pi/b] > > Why does the second output different from the first? I know it has > something to do with the fact that Pi is internally defined in > Mathematica > because a similar result occurs Pi is replaced with E, but what > logic is > being followed? > > -- > ====================================== > L. Dwynn Lafleur > Professor of Physics > University of Louisiana at Lafayette > lafleur at louisiana.edu > ====================================== > Curiously, if you use FullSimplify rather then Simplify you will get: FullSimplify[UnitStep[a-Pi/b], a-Pi/b > 0] 1 The same holds if Pi is replaces by E, or indeed by explicit functions of E or Pi such as Pi^2, E^Pi etc. In all such cases FullSimplify works but Simplify does not work. Strange. Andrzej Kozlowski

**References**:**Simplify UnitStep expressions***From:*"L. Dwynn Lafleur" <lafleur@louisiana.edu>