Path: news.mathworks.com!newsfeed-00.mathworks.com!newsfeed2.dallas1.level3.net!news.level3.com!postnews.google.com!j32g2000yqh.googlegroups.com!not-for-mail
From: Greg <heath@alumni.brown.edu>
Newsgroups: comp.soft-sys.matlab
Subject: Re: fft for beginners
Date: Sat, 4 Jul 2009 11:57:23 -0700 (PDT)
Organization: http://groups.google.com
Lines: 16
Message-ID: <330d7188-b6f2-4253-82f5-4fcf8e27e505@j32g2000yqh.googlegroups.com>
References: <h2mtni$phl$1@fred.mathworks.com> <h2nsnd$c8c$1@fred.mathworks.com>
NNTP-Posting-Host: 69.141.163.135
Mime-Version: 1.0
Content-Type: text/plain; charset=ISO-8859-1
Content-Transfer-Encoding: quoted-printable
X-Trace: posting.google.com 1246733843 32470 127.0.0.1 (4 Jul 2009 18:57:23 GMT)
X-Complaints-To: groups-abuse@google.com
NNTP-Posting-Date: Sat, 4 Jul 2009 18:57:23 +0000 (UTC)
Complaints-To: groups-abuse@google.com
Injection-Info: j32g2000yqh.googlegroups.com; posting-host=69.141.163.135; 
	posting-account=mUealwkAAACvQrLWvunjg50tRAnsNtJR
User-Agent: G2/1.0
X-HTTP-UserAgent: Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 5.1; .NET CLR 
	2.0.50727),gzip(gfe),gzip(gfe)
Xref: news.mathworks.com comp.soft-sys.matlab:552802


PLEASE DO NOT TOPPOST!

On Jul 4, 11:33 am, "Luca Zanotti Fragonara" <Luca_Zano...@libero.it>
wrote:
> Low indexes means low frequencies?
>
> Yes, but remember that the second half of W contains negative frequencies (which usually are useless, but depends from your field of applications).

In particular, if X is real, the frequency components
above the Nyquist freqency are redundant because of
conjugate symmetry about the Nyquist frequency.

Hope this helps.

Greg