making permutations in row elements in a matrix

Hi all,

I have an nxm matrix. I need to make permutations but the row sums must be fixed.

Example;

Original matrix = [15 20; 10 30; 40 30; 50 10; 15 35]

row sums: 35,40,70,60,50.

One of the permutations; [10 25; 20 20; 50 20; 25 35; 20 30]

row sums: 35,40,70,60,50 (row sums must be fixed).

How can I generate permutations like this? Will permutation test work?

If I generate my original matrix with random numbers taken from a specific distribution , how can I permutate the row elements -with holding the row sums fixed-?

Thanks..

Answer 1

[Azzi Abdelmalek]

A=[15 20; 10 30; 40 30; 50 10; 15 35]
id1=A(:,1)/5
id2=A(:,2)/5
id=id1+id2
idx1=arrayfun(@(x) randi(x,1,1),id)
idx2=id-idx1
B=[idx1*5 idx2*5]

[Ayse Kazan]

Thank you so much for the answer, Azzi.

If both the row and coloumn sums must be fixed, what shoul I do?

Sorry, this will be different from my heading but I would appreciate if you could help.. (I dont know if I can change the heading of the question)

[Azzi Abdelmalek]

The answer will be different, please do not change the question, post a new question

[Ayse Kazan]

ok thank you so much.