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From: Greg Heath <heath@alumni.brown.edu>
Newsgroups: comp.soft-sys.matlab
Subject: Re: time and frequency domain
Date: Sun, 11 May 2008 13:47:07 -0700 (PDT)
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On May 11, 9:26=A0am, "Chen Sagiv" <chensagiv...@gmail.com> wrote:
> Greg Heath <he...@alumni.brown.edu> wrote in message
>
> <97e5fc3c-ddbc-4c0c-abd9-
> c52e9a3ea...@s50g2000hsb.googlegroups.com>...
>
> > Corrected for the unforgivable sin of TOP-POSTING!
>
> > On May 11, 7:00=3DA0am, "Chen Sagiv"
> <chensagiv...@gmail.com> wrote:
> > > Greg Heath <he...@alumni.brown.edu> wrote in message
>
> > > <3c59d7c3-618b-44c2-816a-
> > > b58be9319...@24g2000hsh.googlegroups.com>...
>
> > > > On May 10, 3:58=3D3DA0pm, "Chen Sagiv"
> > > <chensagiv...@gmail.com> wrote:
> > > > > Hi,
>
> > > > > It is not important when you plot the abs of the
> FT, but
> > > > > shouldn't you use instead:
>
> > > > > > f1 =3D3D3D zeros(1,512);
> > > > > > f1(128:383) =3D3D3D hamming(256);
>
> > > > > > f2 =3D3D3D zeros(1,512);
> > > > > > f2(128:383) =3D3D3D 1;
>
> > > > > > fft_f1 =3D3D3D fftshift(fft(ifftshift(f1),2048));
> > > > > > fft_f2 =3D3D3D fftshift(fft(ifftshift(f2),2048));
>
> > > > Absolutely not!
>
> > > > Hope this helps.
>
> > > Hi Greg,
>
> > > No, it doesn't help. Can you explain your very short
> > > response ?
>
> > There is no point to using ifftshift.
>
> > When I ran your code the spectra exhibted hashy
> > artifacts.
>
> > Did you cut what you wrote, =A0paste it into a command
> > =A0line, and compare the plots with the originals??
>
> > The results are obviously incorrect.

> Dear Greg,
>
> I refer you to a previous discussion at:
>
> http://www.mathworks.com/matlabcentral/newsreader/view_threa
> d/168642#430044

Let me repeat

When I ran your code the spectra exhibted hashy
artifacts. Did you actually run it??

I read the reference thread. What is your point?

Greg

P.S. You may want to take a look at

fftshift([0 1 2 3 4 5 6 7])
ifftshift([0 1 2 3 4 5 6 7])
fftshift([0 1 2 3 4 5 6 7 8])
ifftshift([0 1 2 3 4 5 6 7 8])