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

# ifft in matlab

Started by ●June 29, 2008

Reply by ●June 29, 20082008-06-29

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

>

>

>

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

>

>

>

Reply by ●June 30, 20082008-06-30

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

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