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  • memory map huge file with boost

    - by HaveF
    I want to handle huge files(TB), after several searches, I find boost could be help boost/interprocess/file_mapping.hpp and I also find the demo code. Because the file that I read is too large(TB), so I think I should create a fixed-size of memory(say 1GB), and remap it when the data isn't on the page. But I don't know how to write this part. I only find another web page, which use "boost.iostreams" to handle this problem. I should use the boost.iostreams? or boost.interprocess.file_mapping? (if this one, please show me some codes), thanks!

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  • why arrayfun does NOT improve my struct array operation performance

    - by HaveF
    here is the input data: % @param Landmarks: % Landmarks should be 1*m struct. % m is the number of training set. % Landmark(i).data is a n*2 matrix old function: function Landmarks=CenterOfGravity(Landmarks) % align center of gravity for i=1 : length(Landmarks) Landmarks(i).data=Landmarks(i).data - ones(size(Landmarks(i).data,1),1)... *mean(Landmarks(i).data); end end new function which use arrayfun: function [Landmarks] = center_to_gravity(Landmarks) Landmarks = arrayfun(@(struct_data)... struct('data', struct_data.data - repmat(mean(struct_data.data), [size(struct_data.data, 1), 1]))... ,Landmarks); end %function center_to_gravity when using profiler, I find the usage of time is NOT what I expected: Function Total Time Self Time* CenterOfGravity 0.011s 0.004 s center_to_gravity 0.029s 0.001 s Can someone tell me why? BTW...I can't add "arrayfun" as a new tag for my reputation.

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