9 Block diagrams

i) We consider the various linear $L:V\to V:$ $y=Lu$ as in $u\to [L]\to y.$

ii) Summing junction $\oplus$ has $y=u_1+u_2$.

iii) Tap $\bullet$ has $y_1=u$, $y_2=u$ (a tap is like an electrical junction, not like a plumbing system)

iv) We can build up more complicated systems as in