Thank you for responding. Yes, I am logged in. --- Den tors 6/1/11 skrev tikkanz <[email protected]>:
> Fra: tikkanz <[email protected]> > Emne: Re: [Jprogramming] FFT > Til: "Programming JForum" <[email protected]> > Dato: torsdag 6. januar 2011 11.30 > Not protected afaics. Are you logged > in? Ric > > -----Original Message----- > From: Bo Jacoby <[email protected]> > Sent: Thursday, 6 January 2011 22:26 > To: Programming forum <[email protected]> > Subject: Re: [Jprogramming] FFT > > The page > http://www.jsoftware.com/jwiki/JohnRandall/FourierTransformAndPolynomialMultiplication > contains the definition > rou=:[: r. 2p1 * i. % ] > I'd like to supplement with the shorter definition > rou=:_1^2%] > but the page is write protected. Why? > - Bo > > --- Den tors 6/1/11 skrev Roger Hui <[email protected]>: > > > Fra: Roger Hui <[email protected]> > > Emne: [Jprogramming] FFT > > Til: "Programming forum" <[email protected]> > > Dato: torsdag 6. januar 2011 07.54 > > http://www.jsoftware.com/jwiki/Essays/FFT > > > > cube =: ($~ q:@#) :. , > > roots =: +...@]^:(0>[) (_1^2%]) ^ i...@-: > > floop =: 4 : 'for_r. i.#$x do. (y=.{."1 y) ] x=.(+/x) > > ,&,:"r (-/x)*y end.' > > fft =: (] floop&.cube 1&ro...@#) > > f. :. ifft > > > > This is a rare practical use of a high rank array. > > ("High" means greater than 4, say.) The only other > > "use" that I know of is the complete tensor of order > n. > > http://www.jsoftware.com/help/dictionary/dccapdot.htm > > > > The expression ,&,:"r in floop can be simplified > to > > ,:"r > > if r is nonzero. This suggested that perhaps the > > definition > > of atom0 ,: atom1 is incorrect. (Should have shape > 2 > > > > instead of 2 1.) > > > > > > > > > ---------------------------------------------------------------------- > > For information about J forums see http://www.jsoftware.com/forums.htm > > > > > ---------------------------------------------------------------------- > For information about J forums see http://www.jsoftware.com/forums.htm > > ---------------------------------------------------------------------- > For information about J forums see http://www.jsoftware.com/forums.htm > ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
