411 REFERENCE · Wikibooks
On 2D Inverse Problems/Fourier coordinates
Reference material by Wikibooks contributors. This retains its source identity and is not 411 news reporting.
Let be a not unit Nth root of unity, i.e. .
The discrete Fourier transform 's given by the symmetric Vandermonde matrix:
For example,Exercise (*). The square of the Fourier transform is the identity transform:Exercise (*).' If an e-network is rotation invariant, then so 's the conductivity equation and the Dirichlet-to-Neumann map is diagonal in the Fourier coordinates (the column vectors of the matrix.