In my literature reviews I found a few things that I can't quite understand. 1. The problem statement, all variables and given/known data I have the following equation: http://img717.yfrog.com/img717/6416/31771570.jpg [Broken] I'm told that by using the eigenvalue factorization: http://img89.yfrog.com/img89/760/83769756.jpg [Broken] , I can change the first equation to: http://img28.imageshack.us/img28/5023/84802099.jpg [Broken] 2. The attempt at a solution I tried changing Equation 2 to just be (A^T)A and then subbing into the first equation, but I can't quite do anything with those inverses. Also, what does the exponent of '-2' mean in the context of a 4x4 matrix? Lastly, what is matrix U? Thank you!