Path: news.mathworks.com!newsfeed-00.mathworks.com!newsfeed2.dallas1.level3.net!news.level3.com!postnews.google.com!q40g2000prh.googlegroups.com!not-for-mail
From: dbd <dbd@ieee.org>
Newsgroups: comp.soft-sys.matlab
Subject: Re: Understanding phase in the FFT
Date: Wed, 29 Jul 2009 20:37:31 -0700 (PDT)
Organization: http://groups.google.com
Lines: 20
Message-ID: <8ea06202-cfd1-44cf-8656-c6c03daa210d@q40g2000prh.googlegroups.com>
References: <h4qfa7$fa0$1@fred.mathworks.com>
NNTP-Posting-Host: 75.11.185.28
Mime-Version: 1.0
Content-Type: text/plain; charset=ISO-8859-1
Content-Transfer-Encoding: 7bit
X-Trace: posting.google.com 1248925051 1320 127.0.0.1 (30 Jul 2009 03:37:31 GMT)
X-Complaints-To: groups-abuse@google.com
NNTP-Posting-Date: Thu, 30 Jul 2009 03:37:31 +0000 (UTC)
Complaints-To: groups-abuse@google.com
Injection-Info: q40g2000prh.googlegroups.com; posting-host=75.11.185.28; 
	posting-account=E_gaFgoAAACfAhF2MzvkivNAUVGQbrBP
User-Agent: G2/1.0
X-HTTP-UserAgent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.8.1.20) 
	Gecko/20081217 Firefox/2.0.0.20 (.NET CLR 3.5.30729),gzip(gfe),gzip(gfe)
Xref: news.mathworks.com comp.soft-sys.matlab:559499


On Jul 29, 2:35 pm, "aaaa Vadimov" <a...@hotmail.com> wrote:
> Hi,
>
> Here the simple code of three series, which differ only by phase. I don't understand why I am not getting phases,which I expect to. Shouldn't I get 0 (or 360), 90 and 45 ? Thanks a lot!
>
> fs = 10;
> t = 0:1/fs:50-1/fs;
>
> x1 = sin(2*pi*t);
> x2 = sin(2*pi*t+pi/2);
> x3 = sin(2*pi*t+pi/4);
> ...

Why do you expect a sine wave to give a phase of 0 with an fft()? The
basis vectors are cos()+i*sin().

Dale B. Dalrymple