How to extract only postive values from a n x n matrix

I have a 100X100 matrix with negative and positive values, and i need to find the sum of each row for values that are greater than zero.

Answer 1

[Guillaume]

m = randi([-20 20], 100); %demo data
sum(m .* (m>0), 2)

would work. Basically, replace negative numbers by 0 and take the sum.