A = size 3 by 4 Matrix of double:
[ 0.7 0.1 -0.9 0 ]
[ -0.3 0 0 0 ]
[ 0.4 -0.3 0.7 -0.8 ]

A (nested-for) = { (0,0)=0.7 (0,1)=0.1 (0,2)=-0.9 (1,0)=-0.3 (2,0)=0.4 (2,1)=-0.3 (2,2)=0.7 (2,3)=-0.8 }
A (iterator) = { (0,0)=0.7 (1,0)=-0.3 (2,0)=0.4 (0,1)=0.1 (2,1)=-0.3 (0,2)=-0.9 (2,2)=0.7 (2,3)=-0.8 }

