Re: RSolve and complex solutions
- To: mathgroup at smc.vnet.net
- Subject: [mg54711] Re: [mg54693] RSolve and complex solutions
- From: Andrzej Kozlowski <akoz at mimuw.edu.pl>
- Date: Mon, 28 Feb 2005 03:26:57 -0500 (EST)
- References: <200502270629.BAA25405@smc.vnet.net>
- Sender: owner-wri-mathgroup at wolfram.com
On 27 Feb 2005, at 07:29, Skirmantas 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?
>
>
>
Are all your equations linear? Otherwise the answer is "obviously no".
A trivial example that satisifes all your stated conditions is
RSolve[a[n]^2 + 1 == 0, a[n], n]
{{a[n] -> -I, a[n] -> I}}
Andrzej Kozlowski
- References:
- RSolve and complex solutions
- From: skirmantas.janusonis@yale.edu (Skirmantas)
- RSolve and complex solutions