bounded random numbers with a certain sum

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Seldeeno 2017-5-5

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https://ww2.mathworks.cn/matlabcentral/answers/338812-bounded-random-numbers-with-a-certain-sum

回答： Image Analyst 2017-5-5

Hello

I am trying to see how I can generate 5 random numbers, each between 0-2, and the sum is given. (I need this as a part of my bigger matrix that is used motivate my sin function later in the simulation.)

Thanks

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Answer 1

Image Analyst 2017-5-5

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/338812-bounded-random-numbers-with-a-certain-sum#answer_265697

See http://www.mathworks.com/matlabcentral/fileexchange/9700-random-vectors-with-fixed-sum

http://blogs.mathworks.com/pick/2006/04/12/uniform-random-samples-with-fixed-sum/

This generates m random n-element column vectors of values, [x1;x2;...;xn], each with a fixed sum, s, and subject to a restriction a<=xi<=b. The vectors are randomly and uniformly distributed in the n-1 dimensional space of solutions. This is accomplished by decomposing that space into a number of different types of simplexes (the many-dimensional generalizations of line segments, triangles, and tetrahedra.) The 'rand' function is used to distribute vectors within each simplex uniformly, and further calls on 'rand' serve to select different types of simplexes with probabilities proportional to their respective n-1 dimensional volumes. This algorithm does not perform any rejection of solutions - all are generated so as to already fit within the prescribed hypercube.