How to add zero vectors and columns in arbitrary places?

I have a matrix that identifies the places where I want the data. For example:

N=[0,1,0,1;0,0,0,0;0,1,0,1;0,0,0,0]|

and a matrix with the same dimensions as the submatrix of N that contains only 1's (it is always a submatrix), for example

B=[1,0.8;0.8,2]

What I need to do is to have a matrix with the same dimensions as N, but with the values in B in the same place were N has ones.

so the answer should be:

BL=[0,1,0,0.8;0,0,0,0;0,0.8,0,2;0,0,0,0]

Thank you, for any advice in advance. :D

Answer 1

[Azzi Abdelmalek]

N=[0,1,0,1;0,0,0,0;0,1,0,1;0,0,0,0]
B=[1,0.8;0.8,2]
N(logical(N))=B

[Gabriel Martinez]

Works perfect!! Thanks a lot

Answer 2

[Adam]

N( N == 1 ) = B;

[Guillaume]

Assuming you're working by rows rather than columns, you may have to transpose both N and B.