comp.lang.idl-pvwave archive - RDF feed
type: channel
description: Messages from Usenet group comp.lang.idl-pvwave, compiled by Paulo Penteado
items: Re: Complex -> Real FFT

Re: Complex -> Real FFT
type: item
description: David Fanning wrote: > > Jeremy Kepner (jvkepner@muse.Princeton.EDU) writes: > >> Does anyone know of a Complex to Real FFT that has >> been implemented in IDL. (Likewise a corresponding >> Real to Complex FFT would also be nice). > > I'm probably missing something deep here, but > doesn't this do what you want? > > result = FLoat(complex_fft_expression) > result = Imaginary(complex_fft_expression) If you don't care about phase information with your FFT data, and instead want just an absolute power measurement (like a spectrum analyzer), you could use power_spectrum = Abs(complex_fft_data) [the abs function returns the value of sqrt(real^2+imaginary^2) if it's argument is complex] Conversely, you could also get the phase info into an array phase_array = Tan(complex_fft_data) [The tan function also nicely works with complex data] From these two arrays you could then go back to the complex array. However, as far as I know, there is no way to obtain the two independent variables of the original complex array after it's been converted to reals. ------------------------------------------------------------ Jeffrey Wasserman - Member of Technical Staff Group 83 Electro-Optical Materials and Devices MIT Lincoln Laboratory Lexington, MA ------------------------------------------------------------ Warning - I am using a government mail server, any un- authorized spam mail will be prosecuted! Change the x's to dots and the y to 'at' sign to respond: wassermanyllxmitxedu ------------------------------------------------------------
creator: Jeff Wasserman
date: 1999-07-26T07:00:00-00:00