# should block diagrams in Direct Form 1/2 contain empty branches to fit structure?

When creating a block diagram in a well-recognized structure (Direct Forms 1&2 in particular), does one remove branches where the coefficient is 0?

This picture includes a coefficient of $b_1=0.00$ . Should the branch be removed or is it reasonable as well to still include it, so the structure is kept and people can easily see it's Direct Form 1?

I plan on using these diagrams for a beginnner's tutorial.

• If you want to right highly efficient real time code, you take it out. If you want to teach a class to beginners, you leave it in. Depends on what you are trying to do – Hilmar Feb 10 '18 at 13:22
• I'd like to use them in a tutorial for beginners. – Jonas Schwarz Feb 10 '18 at 14:01
• @Hilmar I don't even fully agree with you here – most high-performance code (meaning software) runs on CPUs that are pretty good at doing the same thing to consecutive values. It's usually much more efficient to do a superfluous addition and zero multiplication than to have branches or nonlinear memory accesses to avoid them! When implementing this in fixed hardware, I'd fully agree – omit that branch, it only costs space and power. – Marcus Müller Mar 10 '18 at 19:44