Set all elements of a sparse matrix to zero

I have 4 sparse matrices A, B, C, and D .

ABCD = [A  B; C D];

How can I set the all elements of the sparse matrix B and C to zeros?

[Rik]

The easiest way is probably to overwrite them by sparse arrays of the same size.

[James Tursa]

Do you mean you have ABCD and want to 0 out the parts originally associated with the B and C spots? Or do you mean you have A and D and want to built ABCD with effectively 0 for the B and C spots?

[Bruno Luong]

Strictly speaking, your question is trivial to answer!

B(:) = 0;
C(:) = 0;

I challenge you to tell me why this doesn't answer your question.

Just to show how your question is in fact ill-formulated.

Answer 1

[Bruno Luong]

B(:) = 0;
C(:) = 0;