Vectorizing evaluation of cell array of functions

I have an S-by-1 cell array of function handles, each taking one argument---call it 'funcell'. I also have an S-by-1 vector of numeric values---call it 'inputs'. My goal is to obtain a numeric vector of size S-by-1---call it 'output', such that each element j of 'output' contains the corresponding function evaluated at the corresponding numeric value.

In a for loop, this would just be:

for j=1:S
    output(j)=funcell{j}(inputs(j))
end

The problem is that S is very large, so this is slow. Is there a way to vectorize this process for speed?

[Bruno Luong]

"The problem is that S is very large, so this is slow. Is there a way to vectorize this process for speed?"

This is again a wrong preconceived slowness of FOR-LOOP. It is slow because you evaluate many function handles not because it is embeded in a FOR-LOOP.

Answer 1

[James Tursa]

Not sure this will be any faster since the loop is just hidden, but you can try this:

output = arrayfun(@(x,y)x{1}(y),funcell,inputs);

Did you pre-allocate output before your loop? I'm assuming your example was a typo and was supposed to read:

output(j)=funcell{j}(inputs(j))

[Tristan Potter]

Thanks for the suggestion---it yields a modest speed-up, but computation is still pretty slow.

And yes, that was a typo. I've edited the original post accordingly.

[Bruno Luong]

It yields a modest speed-up

Expected, because the slowness is NOT due to the for-loop.