matrix question (finding the smallest number in each row)

I have a matrix B, of size 1455x2. I want a matrix C of size 1455x2 which gives me the matrix B but, if there is a non-negative row, it should be a row of zeros.

Then once I have this C, I want a matrix D which gives me the location of the minimum in each row of C.

Answer 1

[Björn]

 [~,min_col]=min(B,[],2)

This gives you a 1455x1 vector with the column-number of the smallest element in in the rows. To also get the minimum values of each row, you can replace '~' with a variable that you want to assign to those values.