Re: FourierTransform Bug V4

*To*: mathgroup at smc.vnet.net*Subject*: [mg20553] Re: FourierTransform Bug V4*From*: Jane.M.Manderscheid at lerc.nasa.gov (Jane M Manderscheid)*Date*: Sat, 30 Oct 1999 00:14:04 -0400*Organization*: NASA Lewis Research Center*References*: <7v3dqn$64d@smc.vnet.net>*Sender*: owner-wri-mathgroup at wolfram.com

I don't know how to fix it, but the problem may be due to the usage of DiracDelta functions rather than Fourier transforms. Try the following command: Integrate[2 DiracDelta[w-2x],x] -1+UnitStep[-w+2 x] Change the w to y and you'll get a different answer: Integrate[ 2 DiracDelta[y-2 x],x] UnitStep[2 x-y] These results were obtained from V. 4 on unix platforms. Version 3 works correctly. I emailed Wolfram a week ago but have not received a response. Jane Manderscheid NASA Glenn Research Center In article <7v3dqn$64d at smc.vnet.net>, lwalker701 at earthlink.net says... > >FourierTransform of v4 returns incorrect values. For >example, the following is computed in version 4: > >FourierTransform[UnitStep[t], t, w, FourierParameters -> >{1,-1}] > >= -(I/w) - Pi*DiracDelta[w] > >But version 3 correctly returns > >-(I/w) + Pi*DiracDelta[w] > >How can I fix this? Perhaps Unprotect[FourierTransform]... > >Thanks, >Lawrence > > >-- > > >------------------------------------------------------------ > > (\___/) The fear of the LORD is the beginning of > (o\ /o) wisdom: a good understanding have all they > /|:.V.:|\ that do his commandments: his praise > \\:::::// endureth for ever. Psa 111:10 >-----`"" ""`------------------------------------------------ > > Lawrence A. Walker Jr., M.Eng./Ph.D. Candidate > Morgan State University > Clarence M. Mitchell School of Engineering > COMSARE (Center Of Microwave/Satellite And RF Engineering) > Rm: 306-Schafer Phone: (443)885-1453 >------------------------------------------------------------ > > > >