envelope of an oscillatory InterpolatingFunction
- To: mathgroup at smc.vnet.net
- Subject: [mg49780] envelope of an oscillatory InterpolatingFunction
- From: "Stergios J. Papadakis" <stergios.papadakis at jhuapl.edu>
- Date: Sat, 31 Jul 2004 03:14:00 -0400 (EDT)
- Organization: Johns Hopkins University Applied Physics Lab, Laurel, MD, USA
- Sender: owner-wri-mathgroup at wolfram.com
Dear group, I use NDSolve and get an oscillatory InterpolatingFunction with a slowly varying envolope. I would like to extract just the envelope. Right now I am FFTing the InterpolatingFunction, using NMaximize to find the peak and therefore the carrier frequency. Then I step through the InterpolatingFunction using a While loop, one period at a time, and use NMaximize to find the maximum on that each period. This is really slow, and sometimes it just obviously gets it wrong and I can't really figure out why. Is there a better way that I just don't know about? Thanks, Stergios