I am coding in C, i have 3 raw buffers of arrays pre-allocated: A,B,C

I would like to execute a matrix operation C=A*B.
If i use Eigen, i have to wrap my buffers, but when i do the multiplication, it creates another variable then i have to copy the result back to my buffer C.

Is there any way to provide to eigen directly where to store the result?
Do you have any dgemm like interface from Eigen?
Many thanks!