When we add matrix B to A (PETSc Mat), is there a method to drop the non-zero elements in B which **do not** exist in A?

For example, if

A=

[ 1, 0

0, 2]

B=

[1, -1

0, 3]

Can we neglect -1 in B, so that B would have the same sparsity as A?

When we add matrix B to A (PETSc Mat), is there a method to drop the non-zero elements in B which **do not** exist in A?

For example, if

A=

[ 1, 0

0, 2]

B=

[1, -1

0, 3]

Can we neglect -1 in B, so that B would have the same sparsity as A?

1 Like

No, you need to do that yourself.

do you have an idea? can I access every element of the matrix?