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vector operation and loop, which is quicker?

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Hi all: Say in C++, I have a vector of data say: vector<int> array(10000); If I do some calculation on the array, is for loop quicker or some vector/matrix routine defined in libraries like numerical recipes quicker? Thanks

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Implement it both ways and use a profiler to find out.

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it really depends on your implementation and theirs. Using theirs is most likely the fastest way to get working code unless you have to do a lot of hacking and chopping to get your data in the right format for theirs.

as an example, say you are writing a function to find which of a few objects is closer. If you used a library function to calculate the distance it computes the whole distance. Since you only need the relative order of the objects you could write it yourself and use distance squared and save yourself the calculation of multiple square roots. The library writer can't do this since he has promised you distance.

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