Matrix Diagonal Multiplication I have a matrix-vector inner product multiplication $G = X D x$ where $D$ is a diagonal matrix. Now let's say I already know $E = Xx$. Is there a method that I can use to change $E$ into $G$ using $D$ without having to calculate $G$ in full?

I love cheap answers because they help in asking good questions.  So you have $G=XDX^{-1}E$  How do you intend to use $G$ that this does not satisfy?  I don't understand where diagonal comes into this.
