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Re: just doesn't work

  • To: mathgroup at
  • Subject: [mg25385] Re: [mg25346] just doesn't work
  • From: "Rosa Ma. Seco" <ceie at>
  • Date: Fri, 29 Sep 2000 01:06:16 -0400 (EDT)
  • Sender: owner-wri-mathgroup at

Question 1. Try to separate the notion of a text editor from a mathematical
system such as Mathematica. The function ReplaceAll is defined by
 "expr /. rules applies a rule or list of rules in an attempt to transform
 subpart of an expression expr." If you look at your expression in FullForm

FullForm[(4 a^3 b c K Pi Ro)/(15 r^3)]


you'll see that no sub part of it is ever going to be substituted by m.
However, in the text editor context simply use Find and Replace.

Question 2.  Use Simplify:

Simplify[a^2 b c + a b c]
a (1+a) b c

Tomas Garza
Mexico City

Borut L [mailto:justmyname at] wrote:

> I am writing a paper in Mathematica 4.0, and I found it to be
> very powerful
> text editor. However, I encountered some deadly problems, which I cannot
> solve. Thanks for any help!
> 1. How can I replace a symbol m with (4 a b c Pi Ro)/3 in expr
> (4 a^3 b c K Pi Ro)/(15 r^3)
> expr/.(4 a b c Pi Ro)/3 -> m
> just doesn't work
> 2. How Can I 'bring out' a defined part from a sum of two terms.
> e.g.
> Bo[a^2 b c + a b c,a b c] - (would produce) - > a b c (a+1)
> Collect[expr,{a,b,c}]
> just doesn't work.

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