Re: Fourier function...having problems reproducing answers in a paper

*To*: mathgroup at smc.vnet.net*Subject*: [mg54059] Re: Fourier function...having problems reproducing answers in a paper*From*: Paul Abbott <paul at physics.uwa.edu.au>*Date*: Wed, 9 Feb 2005 09:27:34 -0500 (EST)*Organization*: The University of Western Australia*References*: <cua5b2$hh8$1@smc.vnet.net>*Sender*: owner-wri-mathgroup at wolfram.com

In article <cua5b2$hh8$1 at smc.vnet.net>, "elparedblanco" <cire1611 at gmail.com> wrote: > Hi there, > > I am using the Fourier function on a simple list probability > distribution {.5,0,.4,0,0,.1}. The paper I'm reading says I should be > geting an answer like this: > > {1, .35-.2598i, .25+.433i, .8, .25-.433i, .35+.2598i}. > > However this is what Mathematica is returning: > > {.408248 + i, .142887 + .106066i, .102062 - .176777i .326599 + i, > .102062 + .17677i, .142887 - .106066i } > > I assume that these are somehow equivilant. Can some explain how/why? If you compute ift = InverseFourier[{0.5, 0, 0.4, 0, 0, 0.1}] and then normalize, Chop[ift Sqrt[Length[ift]]] you get the same answer (up to numerical round-off) as the paper you're reading. For an explanation, see page 218 of Crandall, R. 1991, Mathematica for the Sciences, Addison-Wesley, Reading, Mass. Cheers, Paul -- Paul Abbott Phone: +61 8 6488 2734 School of Physics, M013 Fax: +61 8 6488 1014 The University of Western Australia (CRICOS Provider No 00126G) 35 Stirling Highway Crawley WA 6009 mailto:paul at physics.uwa.edu.au AUSTRALIA http://physics.uwa.edu.au/~paul