One trivial find → that helped me as well → derivative of matrix → same dimension.
The dimension fits right in.
The substitution trick → very sexy and smart trick.
- (2019). Web.stanford.edu. Retrieved 7 April 2019, from https://web.stanford.edu/~jduchi/projects/matrix_prop.pdf
- (2019). Cal.cs.illinois.edu. Retrieved 7 April 2019, from http://cal.cs.illinois.edu/~johannes/research/matrix%20calculus.pdf