MATLAB: Creating random integer row array each element different upper limit and sum of elements add up to a number

bounded rowfixed sumrandom number

I am looking for a intutuve code to generate 1×6 array where each element is random integer (with in specific upper limit) and sums to a given number.
For example a random array where element lower limit [ 0 0 0 0 0 0] and upper limit [ 9 12 25 6 14 7]. The sum of the random integer number adds up to 24, e.g.
[4 3 8 1 3 4 1]

Best Answer

See this excellent FEX package by John: https://www.mathworks.com/matlabcentral/fileexchange/49795-randfixedlinearcombination. However, It generates fractional numbers. Following code proposes one modification. I don't know how it will change the probability distribution.
lb = [0 0 0 0 0 0];
ub = [9 12 25 6 14 7];
n = numel(lb);
s = 24;
x = round(randFixedLinearCombination(1, s, [1 1 1 1 1 1], lb, ub));
k = sum(x) - s;
if k > 0
    idx = find(x >= (lb+1));
    idx = idx(randperm(numel(idx), k));
    x(idx) = x(idx) - 1;
else
    idx = find(x <= (ub-1));
    idx = idx(randperm(numel(idx), -k));
    x(idx) = x(idx) + 1;
end
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