1. ## Challenge Problem

Find the suffice and necessary condition for two complex matrixs having at least one common eigenvector .

2. Originally Posted by Shanks
Find the suffice and necessary condition for two complex matrixs having at least one common eigenvector .

More than challenging this is a research-level result, and it was proved just 25 years ago: it's called Shemesh Criterion and you can google it, but be warned: it's a rather difficult concept.

Tonio