(adsbygoogle = window.adsbygoogle || []).push({});

Why is the math in the red box necessary? According to this definition, it isn't:

**Physics Forums | Science Articles, Homework Help, Discussion**

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Proving a set of functions is orthogonal

**Physics Forums | Science Articles, Homework Help, Discussion**