# Fast Fourier transform - MATLAB

• MATLAB
• bs19777
In summary, the conversation is about raw data in a specific format and how to plot FFT in MATLAB using this data. The user also asks if any conversion is needed and mentions being new to MATLAB. They are directed to use the fft function and can find plotting information by clicking the index button.
bs19777
I have raw data in following format

Time <-> Ch1 <-> Ch2 <-> Ch3
0.01 <-> 1.6 <-> 1.62 <-> 1.92
0.03 <-> 1.63 <-> 1.62 <-> 1.96
0.05 <-> 1.63 <-> 1.63 <-> 2.04
...so on 1000 raw

PS: those <-> are used in this forum to show as table, in actual data those are separate column.

How can I plot FFT in MATLAB from this data ?

Do I have to convert anything first ?

I am newbi to matlab, any help would be greatly appreciated.

Welcome to PhysicsForums!

If the data is named foo, you can extract say, the third column by typing in:
>>col3=foo(:,3)

(the syntax means extract every row of the third column)

To take the FFT, you use the fft function:
http://www.mathworks.com/help/techdoc/ref/fft.html

You can find plotting information (the 'plot' function) by clicking the 'index' button on the left hand side of the screen.

## What is Fast Fourier transform (FFT) in MATLAB?

Fast Fourier transform (FFT) is a mathematical algorithm used to transform a signal from its original time or spatial domain to the frequency domain. In MATLAB, FFT is a commonly used function for analyzing signals and images, and it is a faster and more efficient implementation of the discrete Fourier transform (DFT).

## How does FFT work in MATLAB?

FFT in MATLAB uses a divide-and-conquer approach to break down a signal or image into smaller sub-signals or sub-images, and then combines them together to calculate the frequency components. It involves complex mathematical computations and utilizes fast algorithms to speed up the process.

## What are the advantages of using FFT in MATLAB?

FFT in MATLAB allows for fast and efficient computation of frequency components, making it useful for analyzing signals and images. It also has built-in functions for windowing, filtering, and data visualization, making it a versatile tool for signal processing applications.

## Can FFT be used for non-periodic signals in MATLAB?

Yes, FFT in MATLAB can be used for non-periodic signals as well. However, it is important to note that FFT assumes a periodic signal and may introduce errors if used on non-periodic signals. In such cases, windowing techniques can be used to reduce these errors.

## What are some other applications of FFT in MATLAB?

Aside from signal and image processing, FFT in MATLAB has various other applications such as system identification, spectral analysis, and filtering. It is also commonly used in digital communication systems, control systems, and biomedical engineering.

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