how about this way: n=10; boolean_M=rand(n,n)>0.5; disp(boolean_M) A=rand(n,n); disp(A); x_V=mean(boolean_M.*A,'r') disp(x_V) Hermes -- Sent from: http://mailinglists.scilab.org/Scilab-users-Mailing-Lists-Archives-f2602246.html