Dear Colleagues In case you might be interested: A 30 pages collection of identities, approximations and related issues regarding matrices, can be found at the following address http://www.imm.dtu.dk/pubdb/views/edoc_download.php/3274/pdf/imm3274.pdf Best regards, Kaare Brandt Petersen -- Kaare Brandt Petersen * http://2302.dk