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MathGroup Archive 1999

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simplifying expressions

  • To: mathgroup at smc.vnet.net
  • Subject: [mg20172] simplifying expressions
  • From: "Richard I. Pelletier" <bitbucket at home.com>
  • Date: Sun, 3 Oct 1999 21:07:39 -0400
  • Organization: @Home Network
  • Sender: owner-wri-mathgroup at wolfram.com

I'm sure this is an elementary question, and I apologize for that.

I'm trying to learn Mathematica (3.0) by working my way thru a
differential geometry text which uses it.

I have worked out the curvature in two ways, for the curve (t^2,t^3,0).
The answer is 6t^2 / speed^3, where speed = (4t^2 + 9t^4)^.5 .

Unfortunately, one of the Mathematica answers has real numbers and the
other has integers, and Mathematica doesn't get zero when I subtract
one from the other.

To be more specific, the two numerators are 6. t^2. and 6 t^2, and the
denominators are 1.5 and 3/2

How do I find out what's going on?

Vale,
   Rip
-- 
Multiplication is not commutative before breakfast.

Richard I. Pelletier
NB eddress: r i p 1 [at] h o m e [dot] c o m


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