how to normalize a uniformly distributed random values such that every row sum of X(:,:,i) should be 1 except for ith row?

X = rand([6,3,6]);

how to normalize a uniformly distributed random values such that every row sum of X(:,:,i) should be 1 except for ith row?

Answer 1

[Walter Roberson]

X = rand([6,3,6]);
Xn = X ./ sum(X,2);
for i = 1 : min(size(X,1),size(X,3))
   Xn(i,:,i) = X(i,:,i);
end

Could it be done without a loop? Probably. Is it worth doing without a loop? That is not clear.

[chan]

Thank you Walter for your reply. When i compile this small code its showing error in the second step

[Walter Roberson]

@IRANI ACHARJAMAYUM

Which MATLAB release are you using? The code I posted needs R2015b or later; if you are using an earlier version nearly 6 years later, you should say so.

[chan]

I am using R2016a version

[Walter Roberson]

X = rand([6,3,6]);
Xn = bsxfun(@rdivide, X, sum(X,2));
for i = 1 : min(size(X,1),size(X,3))
   Xn(i,:,i) = X(i,:,i);
end
Xn(:,:,1)

ans = 6×3

0.4936 0.5068 0.5511 0.5364 0.2268 0.2368 0.6771 0.1878 0.1352 0.2196 0.7094 0.0709 0.4486 0.4937 0.0577 0.2083 0.5217 0.2701

sum(Xn(:,:,1),2)

ans = 6×1

1.5515 1.0000 1.0000 1.0000 1.0000 1.0000

sum(Xn(:,:,2),2)

ans = 6×1

1.0000 2.2510 1.0000 1.0000 1.0000 1.0000

[chan]

Sir could you please help me in this code in modifying...i need every row sum of X(:,:,i) should be 1 except for ith row. This ith row should come from user's choice. if i=3 then all rows should be one except the row 3 in all the matrices...

[Walter Roberson]

i need every row sum of X(:,:,i) should be 1 except for ith row.

The code already does that. sum(Xn(:,:,1),2) is all 1 except for row 1, sum(Xn(:,:,2),2) is all 1 except for row 2.

This ith row should come from user's choice.

What does the user's choice have to do with it?

Your requirements are that all rows should sum to 1 except X(1,:,1), X(2,:,2), X(3,:,3), X(4,:,4)

if i=3 then all rows should be one except the row 3 in all the matrices...

No, that contradicts your earlier requirements that every row sum of X(:,:,i) should be 1 except for ith row. In the case of i = 3, your requirement is that every row sum of X(:,:,3) should be 1 except for row 3, X(3,:,3) not that the sum should be 1 except for row 3 in all of the matrices, such as X(3,:,2) .

If you had asked for every row sum of X(:,:,:) to be 1 except for row i, i chosen by the user, then that would be a different matter.