The derivative of a quadratic form is given by:
$\Delta_{X} X^{T}AX = 2AX$
where A is symmetric.
What is the derivative of the following:
$\Delta_{X} (DX)^{T}A(DX)$,
where $A$ is positive and symmetric and $D$ is not necessarily symmetric?
I would like to rearrange terms such that the $D$ is on the inside of the operator, however, I am unsure of whether I can do this.
Since $D^TAD$ is symmetric, it seems you can replace $A$ in your original result by $D^TAD$.