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MathGroup Archive 2005

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Re: RSolve and complex solutions

  • To: mathgroup at smc.vnet.net
  • Subject: [mg54754] Re: [mg54693] RSolve and complex solutions
  • From: Chris Chiasson <chris.chiasson at gmail.com>
  • Date: Mon, 28 Feb 2005 03:29:17 -0500 (EST)
  • References: <200502270629.BAA25405@smc.vnet.net>
  • Reply-to: Chris Chiasson <chris.chiasson at gmail.com>
  • Sender: owner-wri-mathgroup at wolfram.com

I don't know. You could find out by rationalizing all of the real
coefficients so that Mathematica can use exact calculations in the
RSolve command. When the solution is done, you could inspect it to see
if there are any complex numbers.


On Sun, 27 Feb 2005 01:29:18 -0500 (EST), Skirmantas
<skirmantas.janusonis at yale.edu> wrote:
> It may be a basic math question, but it would be helpful if somebody
> could briefly comment on it. If I have a system of recursion equations
> with real coefficients and solve it numerically step-by-step, all my
> solutions at all time steps are (obviously) real. If, however, I use
> RSolve to get the general formulas for these solutions, some of them
> become complex numbers. My understanding is the imaginary parts of
> these numbers are due to rounding errors and the actual solutions are
> only the real parts. Am I right?
> 
> 


-- 
Chris Chiasson
Kettering University
Mechanical Engineering
Graduate Student
1 810 265 3161


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