MathGroup Archive 2009

[Date Index] [Thread Index] [Author Index]

Search the Archive

Re: Simplify problem

  • To: mathgroup at
  • Subject: [mg95841] Re: Simplify problem
  • From: Bill Rowe <readnews at>
  • Date: Wed, 28 Jan 2009 06:33:21 -0500 (EST)

On 1/27/09 at 6:58 AM, tidy512 at wrote:

>I am using Simplify / FullSimplify etc. to simplify some equations I
>have, but I am unable to coerce Mathematica into automatically
>giving me the form I require for some of the sub-expressions, e.g.

>I'd like

>1/Sqrt[1 + 1/x]

>to be automatically converted to

>Sqrt[x/(1 + x)]

You can make the desired conversion by using Together. That is

In[21]:= 1/Sqrt[1 + 1/x] // Together

Out[21]= 1/Sqrt[(x+1)/x]

But since

In[22]:= LeafCount[%]

Out[22]= 11


In[23]:= 1/Sqrt[1 + 1/x] // LeafCount

Out[23]= 9

Simplify or FullSimplify will clearly not do what you want since
1/Sqrt[1 + 1/x] has a lower LeafCount and therefore simpler by
the definitions of simpler used in these functions.

The real issue is there is no universal definition of simpler
for arbitrary expressions. You could modify
Simplify/FullSimplify to do what you want in this case. But
doing so is likely to have undesirable effects in some other cases.

  • Prev by Date: Re: Real Solutions
  • Next by Date: HDF data Import
  • Previous by thread: Re: Simplify problem
  • Next by thread: Re: Simplify problem