Let's take an example signal: $y=\cos(x)$ about $x=0$.
$\frac{dy}{dx}=-\sin(0)=0$;
$\frac{d^2y}{dx^2}=-\cos(0)=-1$.
It is important to note that one is not simply the square of the other.
Let's take an example signal: $y=\cos(x)$ about $x=0$.
$\frac{dy}{dx}=-\sin(0)=0$;
$\frac{d^2y}{dx^2}=-\cos(0)=-1$.
It is important to note that one is not simply the square of the other.