inverse Fourier transform

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salih
salih am 10 Feb. 2011
hi,
I have a matrix 120x200 called H. inside H, there are some data like x+iy. I'd like to take inverse Fourier of H, I tried to use, ifft command but it takes only one dimensional inverse Fourier. What command should I use or what code should I use to take inverse Fourier of a 120x200 matrix. Thank you
  1 Kommentar
salih
salih am 10 Feb. 2011
I also wrote a code to take inverse fourier of a matrix 120x200 size. is something wrong with the code
function out = invf(H)
for t=1:120
for tao=1:200
b=zeros(120,200);
for f=1:201
b(t,tao) = b(t,tao)+ H(t,f)*exp(1i*2*pi*(5099+f)*tao*10^-3);
end
k(t,tao)= b(t,tao);
end
end
out = k(:,:);

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Akzeptierte Antwort

Brett Shoelson
Brett Shoelson am 10 Feb. 2011
Look at the dimensions of your z matrix. (size(z)). Then make sure the number of x values matches the first dimen
Consider:
a = rand(3,4);
[nrows,ncols] = size(a); %Careful with this syntax if you
% have higher dimensions!
THIS WORKS:
surf(1:ncols,1:nrows, a)
BUT THIS DOESN'T:
surf(1:nrows,1:ncols, a)
Cheers,
Brett
  1 Kommentar
salih
salih am 10 Feb. 2011
thank you buddy, it was very helpful I solved my problem :)

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Weitere Antworten (2)

David Young
David Young am 10 Feb. 2011
ifft2
  2 Kommentare
salih
salih am 10 Feb. 2011
thank you very much David for your help. can you also help me on that.
I'd like to plot 3D of inverse fourier transform. I use the following commands
x=1:120
y=1:200
z=ifft2(H(:,:))
surf(y,x,abs(z))
but I get following error
??? Error using ==> surf at 78
Data dimensions must agree.
Could you tell me how to correct it ?
David Young
David Young am 10 Feb. 2011
See comment on next "answer"

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salih
salih am 10 Feb. 2011
I'd like to plot 3D of inverse fourier transform. I use the following commands
x=1:120;
y=1:200;
z=ifft2(H(:,:));
surf(y,x,abs(z))
but I get following error
??? Error using ==> surf at 78 Data dimensions must agree. Could you tell me how to correct it ?
  2 Kommentare
salih
salih am 10 Feb. 2011
no suggestion ?
David Young
David Young am 10 Feb. 2011
Try
surf(x, y, abs(z))
Remember that the length of x must be the number of columns of z, and the length of y must be the number of rows.

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