Fourier spectrum of "white noise":
Show the logarithmic spectrum, including the first (DC) component:
The spectrum of a "pulse" is completely flat:
Power spectrum of the Thue-Morse nested sequence
Power spectrum of the Fibonacci nested sequence
2D power spectrum of a nested pattern:
Plot the nested pattern:
Find the logarithmic power spectrum:
Find the Fourier transform of the rule 30 cellular automaton pattern:
Logarithmic power spectrum:
Compute discrete cyclic convolutions to smooth a discontinuous function with a Gaussian:
Compute the cyclic convolution:
Show the original and smoothed function:
The convolution is consistent with
ListConvolve:
Here is some periodic data with some noise:
Find the maximum mode in the spectrum:
Find a high-resolution spectrum between modes where the maximum was found:
Determine the period from the frequencies:
m is a circulant differentiation matrix:
Because

the eigenvalues of
m are:
The eigenvectors are the columns of the DFT matrix, so Fourier diagonalizes m:
This allows very efficient computation of
MatrixExp
for a particular vector:
Show the approximate evolution of the heat equation

on the unit interval: