Vector indexing inefficiency question.

Question

Daniel 2014-6-3

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/132266-vector-indexing-inefficiency-question

评论： Daniel 2014-6-3

采纳的回答： Mahdi

在 MATLAB Online 中打开

Hi all,

I am having performance issues with matlab and I was wondering if anybody had any ideas to speed up my algorithm

I have four vectors, a,b,c,d each of varying lengths. Each value inside the vectors represents a particular angle.

a = [1 2 3 5]
b = [2 52 53 51 55 66]
c = [1]
d = [3 6 9]

A set of four values from A, B, C, D represents a particular geometry I need to evaluate. For example, [1 52 1 9] is a geometry [2 2 1 6] is a geometry etc.... I need to do this for every possible combination of geometry available.

currently I have a bunch of nested for loops, and while I know this is inefficient, it helps me for debugging and I wasn't sure how to vectorize when you need to do each geometry, especially when the vectors are of varying lengths.

Anybody have any good ideas?

Thanks,

Dan

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Rick Rosson 2014-6-3

Please post your MATLAB code.

Daniel 2014-6-3

在 MATLAB Online 中打开

a = [1 2 3 5]
b = [2 52 53 51 55 66]
c = [1]
d = [3 6 9]
for i = 1:length(a)
    for j = 1: length(b)
        for k = 1: length(c)
            for r = 1: length(d)
                  data = function( a(i), b(j), c(k) d(r) )
             end
          end
     end
end