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for example,

A is here.

A=[6 7 8 9];

and,

sumA=sum(A)=30;

The element of the matrix that causes the sum to be 30 must be expressed as a value between 4 and 12.

When I calculate directly, the number of cases that can be obtained is 3,4,5,6,7.

In this way, how to create code?

Stephen
on 13 Sep 2017

Duplicated here, this thread apparently abandoned by Kyungmin Kim:

José-Luis
on 8 Sep 2017

If what you mean is that you want the sum of a random array of four elements to be thirty with some condition placed on the last of them:

lims = [4,12];

totVal = 30;

lastElement = randi(diff(lims) + 1,1 ) + lims(1) - 1;

valueToSplit = totVal - lastElement;

frac = rand(1,3);

frac = frac ./ sum(frac);

result = [round(frac.*valueToSplit), lastElement]

sum(result)

Andrei Bobrov
on 8 Sep 2017

Edited: Andrei Bobrov
on 13 Sep 2017

z = 4:12;

out = [];

for jj = 1:numel(z)

k = nchoosek(z,jj);

out = [out;num2cell(k(sum(k,2) == 30,:),2)];

end

"number of rows":

numel(out)

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