I have a problem appearing in the "Problem Solving Videos" about the lectures on symmetric metrices and positive definiteness. David said that the projection matrix has eigenvalues 1 or 0. I don't know the reason and look forward a interpretation.

Question

datanewb · Answer

I'm just starting to study the section on eigenvalues myself.  I looked at the recitation videos, but I did not see one that was led by David.  Could you post a link to the video in question?  Thanks