The $B$ and $C$ coefficients corresponding to the block diagonals are
Display Formula

(25)$B=[b1,11b1,12b1,13b1,14b1,15\cdots b1,21b1,22b1,23b1,24b1,25\cdots b2,11b2,12b2,13b2,14b2,15\cdots b2,21b2,22b2,23b2,24b2,25\cdots b3,11b3,12b3,13b3,14b3,15\cdots \vdots \vdots \vdots \vdots \vdots \ddots ]C=[c1,1c1,2c2,1c2,2c3\cdots ]$