Re: fourier transform of interpolating function
- To: mathgroup at smc.vnet.net
- Subject: [mg55155] Re: fourier transform of interpolating function
- From: Jon Harrop <usenet at jdh30.plus.com>
- Date: Tue, 15 Mar 2005 00:21:37 -0500 (EST)
- Organization: Flying Frog Consultancy Ltd.
- References: <d0rofq$2cp$1@smc.vnet.net>
- Sender: owner-wri-mathgroup at wolfram.com
dumb_founded wrote: > I am trying to get the Fourier tranform of an interpolating function, > but the function Fourier[] only accepts a data table. What can I do? > I am sure some option is available that someone can inform me of. It sounds like you've got some reading to do. :-) Basically, your question probably isn't well defined. It could be taken to mean that you want the analytic Fourier transform of a piecewise function of splines, but I think this is probably not what you want. You probably want to compute the FFT of a discrete sampling of your interpolation function. Peter Pein suggested using Table to extract a discrete sampling and then applying Fourier to get the DFT. This is a start but the "x" values of your interpolation function are then being discarded so the result needs to be multiplied by a phase factor and scaled in "x" to represent the correct (Nyquist) frequency range and scaled in "y" to represent amplitude (i.e. without a factor of "n"). -- Dr Jon D Harrop, Flying Frog Consultancy http://www.ffconsultancy.com