Re: FourierTransform of Sign^2 ?
- To: mathgroup at smc.vnet.net
- Subject: [mg80014] Re: FourierTransform of Sign^2 ?
- From: Jean-Marc Gulliet <jeanmarc.gulliet at gmail.com>
- Date: Fri, 10 Aug 2007 06:41:30 -0400 (EDT)
- Organization: The Open University, Milton Keynes, UK
- References: <f9gv9e$b82$1@smc.vnet.net>
Jung-Tsung Shen wrote: > I tried to evaluate the following Fourier Transform: > > FourierTransform[Sign[y] Sign[y], y, q] > > where Sign is the sign function. Instead of Sqrt[2 Pi]*DiracDelta[q], > Mathematica (v. 5.0, Mac) gives > > -Sqrt[2 Pi]*DiracDelta[q] > > with a minus sign. Is this a bug or I am doing something wrong here? Might be not of great help here, but Mathematica 5.2 and 6.0.1 both return the expected results. In[1]:= $Version FourierTransform[Sign[y]*Sign[y], y, q] Out[1]= 5.2 for Microsoft Windows (June 20, 2005) Out[2]= Sqrt[2 Pi] DiracDelta[q] In[1]:= $Version FourierTransform[Sign[y]*Sign[y], y, q] Out[1]= "6.0 for Microsoft Windows (32-bit) (June 19, 2007)" Out[2]= Sqrt[2 Pi] DiracDelta[q] -- Jean-Marc