Re: Series
- To: mathgroup at smc.vnet.net
- Subject: [mg42704] Re: Series
- From: Jens-Peer Kuska <kuska at informatik.uni-leipzig.de>
- Date: Tue, 22 Jul 2003 04:40:40 -0400 (EDT)
- Organization: Universitaet Leipzig
- References: <bfasni$gqh$1@smc.vnet.net>
- Reply-to: kuska at informatik.uni-leipzig.de
- Sender: owner-wri-mathgroup at wolfram.com
Hi,
ser = (Series[Sin[x - y^2], {x, 0, 3}, {y, 0, 3}] // Normal // Expand)
/.
a_*x^n_.*y^m_. /; n + m > 3 :> 0
???
Regards
Jens
Konstantin L Kouptsov wrote:
>
> When expanding a function of several arguments in series,
> I want to retain only terms having the total power not more than some
> number. For example:
>
> Series[Sin[x - y^2], {x, 0, 3}, {y, 0, 3}]// Normal// Expand
>
> gives
>
> x - x^3/6 - y^2 + x^2 y^2/2
>
> with the unwanted last term of power 4. How to do this in
> elegant/efficient way?
>
> One way is to do
>
> Series[Sin[a x - (a y)^2], {a, 0, 3}] /.{a->1}
>
> but as the function gets more complicated, this way becomes ugly.
>
> --
> Konstantin L Kouptsov
> Department of Physics, Washington State University