If $X$ is a $n\times n$ square matrix and $F$ its Discrete Fourier Transform, is there a way to compute the diagonal $(F_{1,1},\ldots,F_{n,n})$ without explicitly computing the full DFT?
How about for higher dimensional arrays?
2026-05-16 04:19:54.1778905194
Diagonal of multidimensional DFT
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The diagonal of a matrix product (AB) is the dot product of row's of the first matrix (A) with the corresponding column of the second matrix (B).