How to normalize a matrix such that each column sums equal 1

Hello,

I have a matrix A=[1 2 3; 1 3 6] and want to normalize the matrix such that each column sum equals 1.

The normalized matrix should be: P=[0.5 0.4 0.33; 0.5 0.6 0.67]

I tried these codes:

P=normc(A);

P=(A)/sum(A,1);

P=A/norm(A,1);

but they do not result in a matrix with column sums 1.

Can somebody give me some feedback?

Thank you in advance,

Clarisha

Answer 1

[dpb]

You're missing the "dot" operator so the division is matrix divide not element-wise. See

doc ./
doc rdivide % that's a stretch to know the function name, for sure... :)

A=A./sum(A);

Look up how Matlab operates on arrays in documentation for sum to see why this works for what you want with only one argument...

[Clarisha Nijman]

Thanks a lot, it worked!

Answer 2

[Jim Riggs]

[row, col] = size(A);
for i=1:col
   P(:,i)= A(:,i)/sum(A(:,i))
end

[Clarisha Nijman]

Thanks a lot, this also works! Only a semicolon at the end of the third line.