- To: mathgroup at smc.vnet.net
- Subject: [mg119566] Re: querries
- From: Bill Rowe <readnews at sbcglobal.net>
- Date: Fri, 10 Jun 2011 06:38:48 -0400 (EDT)
On 6/9/11 at 5:45 AM, savits at pitt.edu (Savits, Thomas H) wrote: >1) Why does Mathematica not give the value 0 to the expression >(mu*lambda)^(b) - (mu^b)*(lambda^b)? It seems to treat the >expression (mu*lambda) as a new variable. I used the greek letters >from the palette in the actual expression. By default, Mathematica assumes variables are complex. If you assign appropriate complex values to your expression it does not reduce to 0. You can either tell Mathematica to treat the variables as real or use PowerExpand which assumes variables are real. For example, In:= (mu*lambda)^(b) - (mu^b)*(lambda^b) // PowerExpand Out= 0 >2) Many times I cannot get Mathematica to simplify expressions >involving the exponential functions, e.g., it won't combine the >arguments of the Exp functions. Is there a way to force this? Use PowerExpand. Just be aware that the transformations PowerExpand does are not valid for arbitrary complex values.