A = int(10*rand(1,7))
A( A>= 3) = 0 /// \sleftarrow {\begin{minipage}[t]{6cm}{\nf{}indices are given by a boolean matrix \verb+A>=5+}\end{minipage}}
I=find(A== 0)   /// \sleftarrow{\normalfont indices of \verb+A+ entries equal to \verb+0+}