function b = dftmtx(n)
%DFTMTX	Discrete Fourier transform matrix.
%	DFTMTX(N) is the N-by-N complex matrix of values around
%	the unit-circle whose inner product with a column vector
%	of length N yields the discrete Fourier transform of the
%	vector.  DFTMTX(LENGTH(X))*X is the same as FFT(X).
%
%	The inverse discrete Fourier transform matrix is
%	CONJ(DFTMTX(N))/N.   See also FFT and IFFT.

%	C.R. Denham 7-21-88
%	(c) Copyright 1988, by The MathWorks, Inc.

f = 2*pi/n;     % Angular increment.
w = (0:f:2*pi-f/2).' * sqrt(-1);   % Column.
x = 0:n-1;      % Row.
b = exp(-w*x);  % Exponentiation of outer product.

