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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). enter image description here

Armando j18eos
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Carter Nolan
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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 $f'(b)-f'(a)$.

Or did you want to do this numerically? In that case, look up numerical integration/differentiation.

Bobson Dugnutt
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  • actually it is not a function, it's a random signal, and i need the result to be also a signal, i tried with double derivative and integrator, but it doesn't seem to give me a result ! – Carter Nolan Mar 09 '16 at 22:26
  • @CarterNolan Then I'm afraid I don't really know what you're trying to do. – Bobson Dugnutt Mar 09 '16 at 22:28
  • From a mathematical point the question is fully answers, what remains is the implementation in simulink. You get the second derivative using two derivate blocks in a row. – Daniel Mar 09 '16 at 22:37
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    @Daniel If you want OP to see your comment, use a "@CarterNolan" somewhere in your comment. – Bobson Dugnutt Mar 09 '16 at 22:51
  • @Daniel i tried it, but it didnt give me the result i was expecting, i have asked that question in stack, i will be graitful if you can take a look at it please. – Carter Nolan Mar 10 '16 at 14:25
  • For the readers : Lovsov was right, and thanks to Daniel i did build the model, the Simulink Model is here : http://stackoverflow.com/questions/35904160/find-how-much-a-signal-curves-in-simulink?noredirect=1#comment59506165_35904160 – Carter Nolan Mar 10 '16 at 21:17