RE: PowerExpand in mathematica

*To*: mathgroup at smc.vnet.net*Subject*: [mg31871] RE: [mg31843] PowerExpand in mathematica*From*: "David Park" <djmp at earthlink.net>*Date*: Sat, 8 Dec 2001 05:51:48 -0500 (EST)*Sender*: owner-wri-mathgroup at wolfram.com

Peter, I think that the correct answer is 1/t, not -1/t. Nevertheless, this is just the type of problem that PowerExpand might give the incorrect answer. PowerExpand is an operation that in general is done at your own risk. Try a series expansion on the parts of your expression. Or plot your expression and 1/t. Or try this Series[(-1/t)^(3/2) Sqrt[-t], {t, 0, 10}] 1/t + O[t]^4 David Park djmp at earthlink.net http://home.earthlink.net/~djmp/ > From: Peter [mailto:ptrsn2001 at yahoo.com] To: mathgroup at smc.vnet.net > > Hi, > > Is this a known bug, feature? Or I am doing something wrong? > ------------------------------- > Mathematica 4.0 for Linux > Copyright 1988-1999 Wolfram Research, Inc. > -- Motif graphics initialized -- > > In[1]:= PowerExpand[(-1/t)^(3/2) Sqrt[-t]] > > 1 > Out[1]= - > t > --------------------------------- > The correct answer is -1/t, of course. > > Thanks, > Peter >