apply a function to every element of a square matrix

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Salvatore Mazzarino 2012-9-24

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I have a square matrix and I would apply a function to every element of that matrix in the way I get a new square matrix where every element is the result of the function.does it exist a function for the purpose?

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Answer 1

Wayne King 2012-9-24

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编辑：Wayne King 2012-9-24

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Yes, arrayfun()

For example:

    x = randn(10,10)+1i*randn(10,10);
    y = arrayfun(@conj,x);

or

      x = randn(10,10);
      y = arrayfun(@(x) x.^2,x);

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Wayne King 2012-9-24

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Simon's point is a good one here. Both the examples I gave are easily handled just as:

y = conj(x);
% or for the second
y = x.^2;

I was just illustrating the general use of arrayfun().

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Answer 2

Jan 2012-9-24

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Usually arrayfun is not required and wastes time:

x = rand(10, 10);
a = sin(x);
b = x .* x;
c = x .^ 2;

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Answer 3

Image Analyst 2012-9-24

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Don't forget other cases, non-point processing cases, where vectorized solutions don't work, and I don't think arrayfun would work easily either. For example area processing operations like Sobel Filter, Savitkzy-Golay filter, morphological operations, adaptive filters, etc. Some of these have special functions to do them, but in general, for your custom operations, you can use functions like conv2(), imfilter(), nlfilter(), blockproc(), etc.