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.

Question

arun kumar kanakati 2016-7-9

1
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/294469-hi-every-one-i-am-a-new-mtalb-user-how-can-i-impliment-wigner-distribution-and-this-is-availabl

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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Walter Roberson 2016-7-9

What difficulty are you having with the above code?

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Answer 1

Neekar Mohammed 2019-1-2

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/294469-hi-every-one-i-am-a-new-mtalb-user-how-can-i-impliment-wigner-distribution-and-this-is-availabl#answer_354742

@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