To use Mason's gain formula we need to find paths and loops in the SFG. The example SFG has a loop from V1 to Vout to V1 and two Vin to Vout Paths, one direct and one via V1. Both paths touch (have a ...

Assumptions like loop equivalence can fall apart when considering the CFG ( control flow graph) interpretation versus a parse tree one where the former may e.g. merge loops.