- Thread starter
- #1

- Jan 29, 2012

- 661

I have given a link to the topic there so the OP can see my response.What is the derivative of d/dx (x*x') where x is a vector and x' denotes x transpose (note that x*x' is a matrix, and not the norm of x!)

- Thread starter Fernando Revilla
- Start date

- Thread starter
- #1

- Jan 29, 2012

- 661

I have given a link to the topic there so the OP can see my response.What is the derivative of d/dx (x*x') where x is a vector and x' denotes x transpose (note that x*x' is a matrix, and not the norm of x!)

- Thread starter
- #2

- Jan 29, 2012

- 661

it is easy to prove the relation on $(\alpha,\beta)$ $$\frac{d}{dx}(AB)=\left(\frac{d}{dx}A\right)B+A \left(\frac{d}{dx}B\right) $$

as a consequence $$\frac{d}{dx}(AA^T)=\left(\frac{d}{dx}A\right)A^T+A\left(\frac{d}{dx}A^T\right)=\left(\frac{d}{dx}A\right)A^T+A\left(\frac{d}{dx}A\right)^T$$