# How to define the curvature of a function in simulink

English is not my native language so be tolerent please, you can edit the question as you pleases.

I have a model in simulink (matlab) where I have a function (for example $f(x)$ like in the image), I need a block in simulink (or at least a mathematical explanation), that takes this signal as input and gives me a value proportional to the curvature of my function (for example the part pointed with 1 and 2 in the image).

How much $f(x)$ curves is given by it's second derivative $f''(x)$.
To find how much it curves over an interval, just integrate it over that interval, which is the same as evaluating the first derivative in the interval, i.e. if the interval is $[a,b]$ then the curvature in the interval is $f'(b)-f'(a)$.