@article{BorndoerferFerreiraMartin1998, author = {Ralf Bornd{\"o}rfer and Carlos Ferreira and Alexander Martin}, title = {Decomposing Matrices into Blocks}, journal = {SIAM J. Optim.}, volume = {9}, number = {1}, pages = {236 -- 269}, url = {http://opus.kobv.de/zib/volltexte/1997/285/}, year = {1998}, }