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chebwin

PURPOSE ^

% Usage: chebwin (n, at)

SYNOPSIS ^

function w = chebwin (n, at)

DESCRIPTION ^

% Usage:  chebwin (n, at)
%
% Returns the filter coefficients of the n-point Dolph-Chebyshev window
% with at dB of attenuation in the stop-band of the corresponding
% Fourier transform.
%
% For the definition of the Chebyshev window, see
%
% * Peter Lynch, 'The Dolph-Chebyshev Window: A Simple Optimal Filter',
%   Monthly Weather Review, Vol. 125, pp. 655-660, April 1997.
%   (http://www.maths.tcd.ie/~plynch/Publications/Dolph.pdf)
%
% * C. Dolph, 'A current distribution for broadside arrays which
%   optimizes the relationship between beam width and side-lobe level',
%   Proc. IEEE, 34, pp. 335-348.
%
% The window is described in frequency domain by the expression:
%
%          Cheb(n-1, beta * cos(pi * k/n))
%   W(k) = -------------------------------
%                 Cheb(n-1, beta)
%
% with
%
%   beta = cosh(1/(n-1) * acosh(10^(at/20))
%
% and Cheb(m,x) denoting the m-th order Chebyshev polynomial calculated
% at the point x.
%
% Note that the denominator in W(k) above is not computed, and after
% the inverse Fourier transform the window is scaled by making its
% maximum value unitary.
%
% See also: kaiser

CROSS-REFERENCE INFORMATION ^

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