Dot indexing is not supported for variables of this type.

Dot indexing is not supported for variables of this type.

Error in final (line 20)

O=fft2(o,N256,N256); PHI_o=O. conj(O);

[Rik]

What is your question? Why did you expect this code to work? What did you want to do?

Answer 1

[Chunru]

% avoid use variable such as o and O
x = rand(256, 236);
y = fft2(x,256,256); 
% assume that you are computing the power
p = y.* conj(y);   
% alternatively
% p = abs(y).^2;

Answer 2

[Image Analyst]

You have

PHI_o=O. conj(O);

So, because there is a dot after O you're telling MATLAB that the (poorly named) "O" is a structure or class. It may be -- we have no idea because you didn't tell us how you instantiated O. But you can't have a space after the dot, and that is what you have so it threw the error. Perhaps you meant to have no space

PHI_o = O.conj(O);