MATLAB: Set the values to nan

Question

tb1=[1 2 3 ; 4 5 6 ; 7 8 9]; A1=[0 0 1;1 1 1;0 1 1];

I need to create a new array B1=[nan nan 3;4 5 6;nan 8 9]

when A1=0, then B1 should be nan otherwise it should take the values in tb1.

Answer 1

>> B1 = tb1;

>> B1(A1==0) = NaN;