# Simplifying matrix equation

• November 7th 2012, 02:33 AM
Glitch
Simplifying matrix equation
Hey folks. I'm having trouble understanding the transition from line three to line four, in particular where the $\vec{y}^T \vec{y}$ part gets to. When I tried it I get what's in line four, but with $\vec{y}^T \vec{y}$ as an additional term. What am I missing here?
http://i.imgur.com/pQyX5.png
• November 8th 2012, 02:09 AM
Glitch
Re: Simplifying matrix equation
Can nobody help? To add more context, the result is a real number, which is why line three is identical when the trace is taken.
• November 9th 2012, 09:33 PM
Glitch
Re: Simplifying matrix equation
I think I just realised what it is. They took the derivative of that term, which becomes 0. Silly me.