A = [ 12.3 15.5 14.3 ; 14.5 11.7 21.2 ;  -9.8 10.5 12.3 ]
B = [ 3.4 -11.6 21.9 ; 7.6 19.7 11.3 ; 14.0 23.4 17.7 ]
C = [ 1 3 5 8 ; 2 9 4 1 ; 5 2 1 9; 10 5 3 8]