Re: Algebraic Manipulation
- To: mathgroup at smc.vnet.net
- Subject: [mg46175] Re: [mg46159] Algebraic Manipulation
- From: Oleksandr Pavlyk <pavlyk at phys.psu.edu>
- Date: Tue, 10 Feb 2004 00:05:42 -0500 (EST)
- Organization: Penn State University; Department of Physics
- References: <200402091054.FAA20968@smc.vnet.net>
- Reply-to: pavlyk at phys.psu.edu
- Sender: owner-wri-mathgroup at wolfram.com
Hi David,
I have got to your results using FullSimplify with assumptions:
expr = x*y*(-(z^2/(r^2*(x^2 + y^2))) - 1/(r*(k + r)) + 1/(x^2 + y^2));
FullSimplify[expr, {r >= 0, r^2 == x^2 + y^2 + z^2}]
Best,
Sasha
David Park wrote:
> Dear MathGroup,
>
> I'm always interested in Mathematica techniques for manipulating and simplifying algebraic expressions. I came across the following problem, which I was only able to do with a fair amount of difficulty.
>
> expr = x*y*(-(z^2/(r^2*(x^2 + y^2))) - 1/(r*(k + r)) + 1/(x^2 + y^2))
>
> where
>
> r^2 == x^2 + y^2 + z^2
>
> reduces to
>
> (k*x*y)/(r^2*(k + r))
>
> I wonder if anyone can show an elegant or short method to do the simplification?
>
> (The problem arose in calculating the components of the Schwarzschild metric in Cartesian coordinates.)
>
> David Park
> djmp at earthlink.net
> http://home.earthlink.net/~djmp/
>
--
Office: 6H Osmond Web: http://www.pavlyk.com
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
No trees were destroyed to send this mail,
but a lot of electrons were terribly disturbed.
- References:
- Algebraic Manipulation
- From: "David Park" <djmp@earthlink.net>
- Algebraic Manipulation