changing the structure of a matrix according to a characteristic matrix

I have a matrix (I am calling it characteristic):

=

0 1 1

0 0 1

1 1 1

and another one (which has to be changed):

b =

9 8 7

3 2 7

4 5 3

What I want is to make certain operation on b to remove elements that are in the position of 0 in matrix .

=

0 8 7

0 0 7

4 5 3

Any idea how to do it?

Answer 1

[Sudhakar Shinde]

Use elementwise (.) operator :

Xa=[0 1 1;0 0 1;1 1 1]
b=[9 8 7;3 2 7;4 5 3]
b.*Xa