Moose Peterson has written a lot on this topic. Basically, the matrix meter is complex, and every camera model pretty much has a slightly different version because Nikon is constantly tweaking it. Once you understand how the matrix meter reacts, you can in theory apply exposure comp on top of it and get the results you want. Another situation where you can use comp with matrix is when a solid color fills your viewfinder. in that case, the matrix meter effectively becomes a regular single zone averaging meter.