Re: Problem plotting high-order Laguerre polynomials
- To: mathgroup at smc.vnet.net
- Subject: [mg64235] Re: Problem plotting high-order Laguerre polynomials
- From: AES <siegman at stanford.edu>
- Date: Tue, 7 Feb 2006 03:36:09 -0500 (EST)
- Organization: Stanford University
- References: <dqn7br$l3v$1@smc.vnet.net> <ds7003$8pq$1@smc.vnet.net>
- Sender: owner-wri-mathgroup at wolfram.com
In article <ds7003$8pq$1 at smc.vnet.net>, Paul Abbott <paul at physics.uwa.edu.au> wrote: > > I'm doing some work which involves plotting fairly high-order Laguerre > > polynomials, up to 200 or so. I've been getting some very strange and > > obviously incorrect results which seem to have to do with the order of > > evaluation. (I'm using Mathematica 5.0, but I've checked it in 5.2 and I In plotting Laguerre polynomials up to orders of 60 or thereabouts several years, I began to get what seemed to be round-off errors -- or something -- zigs and zags in numerical results anyway with small changes in parameters. I found I could apparently avoid this simply by using purely integer or rational fraction arguments (plus Pi, and the like). E.g., to explore +/-0.1% variations about argument Pi/6, I'd use (999 Pi/6000), (1001 Pi/6000), and so on. Purely a kludge, but seemed to work.