How to call a function with rows of a matrix?

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UCL student
UCL student 2014-10-29
编辑： Stephen23 2014-10-30
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.
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Julia
Julia 2014-10-30
编辑：Julia 2014-10-30
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.

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回答（2 个）

the cyclist
the cyclist 2014-10-30
编辑：the cyclist 2014-10-30
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.
Stephen23
Stephen23 2014-10-30
编辑：Stephen23 2014-10-30
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.

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