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Re: Transformations in expressions

  • To: mathgroup at smc.vnet.net
  • Subject: [mg91915] Re: [mg91874] Transformations in expressions
  • From: Bob Hanlon <hanlonr at cox.net>
  • Date: Fri, 12 Sep 2008 05:30:18 -0400 (EDT)
  • Reply-to: hanlonr at cox.net

Use ReplaceAll ( /. )

Log[x^2 + y^3]/Sin[x^2 + y^3] /. x^2 + y^3 -> z

Csc[z]*Log[z]

or

Simplify[Log[x^2 + y^3]/Sin[x^2 + y^3], z == x^2 + y^3]

csc(z) log(z)

In both cases, 1/Sin[z] is automatically converted to Csc[z] as a simpler form.

I do not understand your second question.


Bob Hanlon

---- Miguel <misvrne at gmail.com> wrote: 

=============
Hi all,
How can I to transform a specific expression to other by substitution
of a part of it.

For example, I want to transform the expression Log[x^2+y^3]/
Sin[x^2+y^3] in Log[z]/Sin[z] by substitution x^2+y^3 --> z.

And other question: Is the new expression dependent of z. I see it is,
but how can I to programar it.

Thanks


--

Bob Hanlon



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