MATLAB: Random numbergeneration with constraints

constraintsrandom number generator

Hi,

I want to generate a random matrix, with two constraints 1.the sum of each row of the matrix is less or equal to let's say 60. 2.And the values must be within a specified range, say between 10 and 20.

Can anyone help me with this?

Thank you so much for your help!

Best Answer

 ulim=20;    %max value
llim=10;    %min value
rowlim=60;  %max sum for each row
m=5;    %rows
n=4;    %columns
 RMat=rand(m,n)*(ulim-llim)+llim;
Rsum=sum(RMat,2);
Rcheck=Rsum>rowlim;
while any(Rcheck) %replace any row whose sum is > rowlim
    I=find(Rcheck);
    RMat(I,:)=rand(length(I),n)*(ulim-llim)+llim;
    Rsum=sum(RMat,2);
    Rcheck=Rsum>rowlim;
end
disp(RMat)

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I love this kind of problems. First of all, Matlab comes with a debugger that tell you in which part you are losing your time (It's called Run and Time). After running it, it says that the while loop is really slow, so you have to search one way to make the condition succesful in the first attemp. I have try a solution with some other modifications like the if condition which is achieve by the while.

tic
K = 10;
mult_nbrOfSubCarriers = 2;
nbrOfSubCarriers = mult_nbrOfSubCarriers*ones(1, K);
nt_L = 10;
nr_L = 3*ones(1, nt_L);
ulim_c = 1;    % max value of each element
llim_c = 0;    % min value of each element
sumlim_c = 1;
max_nr_L = max(nr_L(:));
numel_nr_L = numel(nr_L);
c0 = zeros(max_nr_L, numel_nr_L, K, mult_nbrOfSubCarriers);
sumlim_c2 = (sumlim_c - llim_c)/(ulim_c-llim_c);
for k = 1 : K
    for m = 1 : nbrOfSubCarriers(k)
        RMat = rand(max_nr_L, numel_nr_L);
        sum_RMat = sum(RMat(:));
        if sum_RMat > sumlim_c2
            RMat = RMat./sum_RMat.*sumlim_c2;
        end
        c0(:,:,k,m) = RMat.*(ulim_c-llim_c) + llim_c;
    end
end
toc

Best Answer

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