Mathematica 9 is now available
Services & Resources / Wolfram Forums / MathGroup Archive
-----

MathGroup Archive 2007

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

Search the Archive

Simplifying Log[a] + Log[expr_] - Log[2 expr_]: Brute force necessary?

  • To: mathgroup at smc.vnet.net
  • Subject: [mg81671] Simplifying Log[a] + Log[expr_] - Log[2 expr_]: Brute force necessary?
  • From: "W. Craig Carter" <ccarter at mit.edu>
  • Date: Mon, 1 Oct 2007 04:46:19 -0400 (EDT)

Hello,
This works as I would hope it would:

Simplify[Log[a^2] + Log[b^2] - Log[-2 b^2],
  Assumptions -> Element[a, Reals] && Element[b, Reals]]

It returns -Log[-2/a^2]

However, something a little more complicated:

Simplify[
Log[4] -
   - 2 Log[-2 ((R + x)^2 + y^2 + (z - zvar)^2)]
    +    2 Log[(R + x)^2 + y^2 + (z - zvar)^2]),
  Assumptions ->
{Element[zvar,Reals], Element[x,Reals],Element[y, Reals], Element[z, Reals}]

doesn't simplify. I can't see a way to do this, but brute force.

Any ideas?
Thanks,

W. Craig Carter



  • Prev by Date: Re: 3D graphics resize unintentionally when rotated
  • Next by Date: Re: 3D graphics resize unintentionally when rotated
  • Previous by thread: Re: Re: 3D graphics resize unintentionally when rotated
  • Next by thread: Re: Simplifying Log[a] + Log[expr_] - Log[2 expr_]: Brute force necessary?