How to do inflection points on graphs in Simulink

How to get an inflection point on my graph, also if you could show me how to put axies on the graph that would be very helpfull.

[Benjamin Thompson]

What is wrong with your sample graph right now?

[Alex Walton]

Nothing-I hope what are you suggesting?

[Mathieu NOE]

hi

woud suggest you to export the simulink data to the matlab workspace for easier post processing

can you share it ?

what point in your graph are you looking for ?

[Mathieu NOE]

hello

problem solved ?

Answer 1

[arushi]

Hi Alex,

I understand that you are trying to get the coordinates of the inflexion point on the graph.

You can follow these steps to get the coordinates of the inflexion points:-

1. Use the Curve Fitting toolbox to obtain an approximate functional equation for the graph displayed by the Scope block. This will provide you with an equation that represents the curve.
2. Compute second derivative of the function using 'diff' function .
3. Use a conditional statement to detect sign changes in the second derivative.
4. Store the coordinates of the inflection points in a variable

For additional information regarding 'diff' function and Curve Fitting toolbox please refer to the following documentations:

https://www.mathworks.com/help/symbolic/differentiation.html

https://www.mathworks.com/products/curvefitting.html

I hope it helps!

[Mathieu NOE]

Would suggest gradient instead of diff for differentiation