[tim_hutton]

SmoothLife uses two disks around each point to determine the instantaneous rate of change. Inside each disk the values are summed. This is a convolution with a disk filter.

http://en.wikipedia.org/wiki/Convolution

As it says on that page, FFT is often used for convolution because it is fast: after applying a discrete Fourier transform to the kernel and the image, the resulting images must only be multiplied together before applying an inverse FFT.

http://en.wikipedia.org/wiki/Discrete_Fourier_transform

[ghostfish]

Ah, thanks for the information. I'm familiar with signal processing, so the only way I'm used to seeing convolutions is through the multiplication of FFTs. I wasn't even considering the "regular" way.

[tomrod]

That's so cool. I love to see real world applications of convolutions.

I wonder if there is an application of Gershgorin's Disc theorem here?

[tim_hutton]

I see something about a circle that contains the eigenvectors of a matrix. How does that apply here?