How to call a function with rows of a matrix?

Hey,

I would like to vectorize a function call that I call with rows of a matrix. How can I implement it without a for loop?

Thanks.

[the cyclist]

There is not remotely enough detail here to answer. Think from our perspective on this.

[James Tursa]

http://www.mathworks.com/matlabcentral/answers/6200-tutorial-how-to-ask-a-question-on-answers-and-get-a-fast-answer

[UCL student]

Sorry, a bit of code

for looper=1:10000
Res = aFunction(Mat(looper,:),Mat2(looper,:))
end

Mat is 10000*6, Mat2 is 10000*9, and I would like to pass them row by row to the function aFunction. Thanks.

[Julia]

Your Res will be overwritten in each loop iteration.

If your function aFunction takes only vectors as its input and has a single number as output, I don't see a method to omit the loop.

[UCL student]

I would like Res to be a vector of results.

Answer 1

[the cyclist]

Res = zeros(10000,1);
for looper=1:10000
  Res(looper) = aFunction(Mat(looper,:),Mat2(looper,:))
end

Note that the first line, preallocating memory is important for the loop to operate efficiently.

If you want to post your aFunction code, it might be possible to identify a way to eliminate the loop entirely.

Answer 2

[Stephen23]

One easy way is to use num2cell to split the numeric arrays into rows/columns/..., and then cellfun on the resulting cell arrays (change the variable names to suit):

out = cellfun(@fun,num2cell(M1,2),num2cell(M2,2),...);

This method assumes that @fun operates on a vector and returns a scalar.

Alternatively you could use the table data class, which supports the function rowfun.