# What is circular convolution?

1. Mar 5, 2013

### dexterdev

Hi PF,
What is circular convolution? Why do we need such an operation if we have linear convolution, What is its basic difference of both convolutions. Is circular convolution used only in frequency domain?

-Devanand T

2. Mar 5, 2013

3. Mar 6, 2013

### rbj

that's a good pdf.

$$((n))_N \ \triangleq \ n\,\bmod\,N \ = \ n - N \left\lfloor \frac{n}{N} \right\rfloor$$

this just makes the index $n$ wrap around so that it is always $0 \le n < N$ . that's what makes it circular.

Last edited: Mar 6, 2013
4. May 7, 2014