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ifft in matlab

Started by edu_forme June 29, 2008
i want to compute the ifft of the following data
data=[0 1 1 0]

in matlab it should return me a single value but it is giving me a
column of values can anybody explain this to me and secondly how matlab
carries out the ifft , how can it be done by hand to verify the result
thanks
Your question is a bit confuse. It is better that you analyze how the
fft/ifft works.
You can use Google e.g. This is a numerical implement*ation of the Fourier
Transform.
To work correctly, you have to respect the Nyquist Theorem and the input
vector needs
a number of points (typically a power of 2 like 10 , 20) to define the
wave form.
In output the fft produce a vector of length equal to that in input
Bye
*

On Sun, Jun 29, 2008 at 8:05 AM, edu_forme wrote:

> i want to compute the ifft of the following data
>
> data=[0 1 1 0]
>
> in matlab it should return me a single value but it is giving me a
> column of values can anybody explain this to me and secondly how matlab
> carries out the ifft , how can it be done by hand to verify the result
> thanks
>
>
>
Hi,
Your assumption that the ifft should give u only 1 value, is wrong. You will 4 values; remember IFFT/FFT is a transform operation you will get as many ifft points as fft points provided you do not zero-pad or clip your data. [0.5000, -0.2500 + 0.2500i, 0, -0.2500 - 0.2500i] is the correct IFFT of your data points. Maybe if I know some more details on what you are trying to do, I can provide more information.
Amit Pathania

--- On Sun, 6/29/08, arkkimede wrote:
From: arkkimede
Subject: Re: [matlab] ifft in matlab
To: "edu_forme"
Cc: m...
Date: Sunday, June 29, 2008, 10:55 PM

Your question is a bit confuse. It is better that you analyze how the fft/ifft works.
You can use Google e.g. This is a numerical implementation of the Fourier Transform.
To work correctly, you have to respect the Nyquist Theorem and the input vector needs

a number of points (typically a power of 2 like 10 , 20) to define the wave form.
In output the fft produce a vector of length equal to that in input
Bye
On Sun, Jun 29, 2008 at 8:05 AM, edu_forme wrote:

i want to compute the ifft of the following data

data=[0 1 1 0]

in matlab it should return me a single value but it is giving me a

column of values can anybody explain this to me and secondly how matlab

carries out the ifft , how can it be done by hand to verify the result

thanks