Apply function to each column of matrix for all columns without for loop

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Jeongseop Lee
Jeongseop Lee 2018-9-6
编辑： Greg Heath 2018-9-7
Hi all,
I have a function "Func(X)" which operations on n-by-1 single column matrix "X" and outputs a scalar quantity. I also have a n-by-m matrix "A" that I would like to apply "Func" for all m columns in "A" and obtain 1-by-m matrix, say B, as a result without using for loop or any iterative definitions. What is the best way to proceed with this?
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Jeongseop Lee
Jeongseop Lee 2018-9-6
编辑：Jeongseop Lee 2018-9-6
The actual calculation of B is much more complicated that takes cascades of multiple functions and B is an optimization fitness product for given population A in neural network. But all this detail is highly irrelevant for my question here. I just want a simple, elegant way that is non-iterative definition that applies a function to each column of a given matrix for all columns without iterative definition.

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Matt J
Matt J 2018-9-6
编辑：Matt J 2018-9-6
There is no general way that is more efficient than a for-loop, but if you are just trying to hide the loop, then you can do things like this:
B=cell2mat( arrayfun(@(i) Func(A(:,i)) , 1:size(A,2), 'uni',0) );
or
B = splitapply(@Func,A,1:size(A,2));

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Greg Heath
Greg Heath 2018-9-7
编辑：Greg Heath 2018-9-7
The MATLAB CONVENTION is that functions operate on matrix columns.
Therefore, it is only with user-defined functions that operations on rows occur.
Hope this helps.
Thank you for formally accepting my answer
Greg

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