Circular-convolution using fft(x) and ifft(X)

Circular convolution using properties of Discrete Fourier Transform.
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Updated 26 Aug 2018

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Step-1: Obtain the N-point DFTs of the sequences x (n) and h (h):
x (n) → X (k)
h (n) → H (k)
Step-2: Multiply the two sequences X (k) and H (k):
Y (k) → X (k) H (k) ,for k=0,1,2,...,N-1
Step-3: Obtain N-point IDFT of the sequence Y(k),to yield the final output y(n)
Y (k) → y (n), for n=0,1,2,.....,N-1

e.g.

Enter x(n):
[1 1 1 1 1 0 0 0]
Enter h(n):
[1 1 1 1 1 0 0 0]
First Sequence x(n) is:
1 1 1 1 1 0 0 0

Second Sequence h(n) is:
1 1 1 1 1 0 0 0

Convoluted Sequence y(n) is:
2 2 3 4 5 4 3 2

Cite As

Ashutosh Rout (2026). Circular-convolution using fft(x) and ifft(X) (https://www.mathworks.com/matlabcentral/fileexchange/68633-circular-convolution-using-fft-x-and-ifft-x), MATLAB Central File Exchange. Retrieved .

MATLAB Release Compatibility
Created with R2016a
Compatible with any release
Platform Compatibility
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Version Published Release Notes
1.0.0