Hi every one, I am a new mtalb user... how can I impliment wigner distribution? and this is available in online but I am unable to implimenting... Please suggest me, thank you very much in advance.

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arun kumar kanakati
回答： Neekar Mohammed 2019-1-2
function W = mywigner(Ex)
%MYWIGNER: Calculates the Wigner distribution from a column vector
%
% W = mywigner(Ex)
%
% W = output Wigner distribution
% Ex = Input electric field (MUST be a column vector
%
% Notes:
% W = Int(-inf..inf){E(x+y)E(x-y)exp[2ixy]}
%
% E(x+y) & E(x-y) are calculated via a FFT (fast Fourier transform) using the
% shift theorem. The integration is performed via a FFT. Thus it is important
% for the data to satisfy the sampling theorem:
% dy = 2*pi/X X = span of all x-values dy = y resolution
% dx = 2*pi/Y Y = span of all y-values dx = x resolution
% The data must be completely contained within the range x(0)..x(N-1) &
% y(0)..y(N-1) (i.e. the function must fall to zero within this range).
%
% v1.0
%
% Currently waiting for update:
% Remove the fft/ifft by performing this inside the last function calls
% Allow an arbitrary output resolution
% Allow an input vector for x (and possibly y).
if (size(Ex, 2)-1)
error('E(x) must be a column vector');
end
N = length(Ex); % Get length of vector
x = ifftshift(((0:N-1)'-N/2)*2*pi/(N-1)); % Generate linear vector
X = (0:N-1)-N/2;
EX1 = ifft( (fft(Ex)*ones(1,N)).*exp( i*x*X/2 )); % +ve shift
EX2 = ifft( (fft(Ex)*ones(1,N)).*exp( -i*x*X/2 )); % -ve shift
W = real(fftshift(fft(fftshift(EX1.*conj(EX2), 2), [], 2), 2)); % Wigner function

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回答（1 个）

Neekar Mohammed
Neekar Mohammed 2019-1-2
@Walter Could you please clarify the terms in the code? I donot understand why we defined x,X, and why in the costraction of E(x-y), E(x+y) we have exp(i xX/2)?
Thanks
Neekar

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