how to efficiently update one element in a matrix conditioned on another element

Hi,

Do you know how to do this? I have a matrix M=[2,3,2;-1,2,3]. I would like to check in any row, if there is a number is less than 0. If so, I let the second column of that row is equal to -Inf. So in this case, as M(2,1)<0.So I update M as [2,3,2;-1,-Inf,3].

I understand I probably can write a loop to do so. But the problem is I need to deal with a big matrix other than M here, which is only 2*3. I will like to speed up the process. So I would like to know if there is an more efficient way to do so? Could any one help me about this please?

Answer 1

[the cyclist]

M(any(M<0,2),2) = -Inf;