Which topic(s) does this matrix come from? What is the name of this matrix?
$$\pmatrix{1&1&1\\1&\omega&\omega^2\\1&\omega^2&\omega}$$
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10That's a Vandermonde matrix, as well as the matrix of the discrete Fourier transform of size $3$... It is not quite clear what the purpose of this question is, though! – Mariano Suárez-Álvarez Feb 10 '12 at 05:28
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2We are assuming that $\omega$ here is a root of unity, of course (too bad OP did not define his/her notation)... if not, then it's just some symmetric matrix. – J. M. ain't a mathematician Feb 10 '12 at 05:44
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This is the discrete Fourier transform matrix of size $3$. It naturally appears mathematically in the representation theory (don't be intimidated by this!) of the cyclic groups $\mathbb{Z}/n\mathbb{Z}$, as well as practically in signal processing and related fields.
Qiaochu Yuan
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