Worth checking the Wikipedia page on matrix calculus to see which version of the notation you use! This is in numerator (iirc) and so d (vec x) / d(t) = (vec x)

Worth checking the Wikipedia page on matrix calculus to see which version of the notation you use! This is in numerator (iirc) and so d (vec x) / d(t) = (vec x). I was used to d (vec x) / d(t) = transpose(vec x), and so this cookbook confused me for ages :S