how to find inflection points in an array consisting of several lines with different slopes

[weitong]

Please see the following graph. These points is plotted from an array(1D) vs. index. It consists of several strictly straight lines with different slopes. I  wish to find the indexes of those inflection points (red arrows indicated).  Is there any function or method?

[GerdW]

Hi weitong,

calculate the slope for each pair of points. When the slope changes you found an inflection point…

[altenbach]

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@weitong wrote:

It consists of several strictly straight lines with different slopes.

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If you have completely noiseless data, this is trivial. Where does the data come from?

What have you tried so far?

[weitong]

These data points are generated by user defintion.  They are generated piece by piece, however they are stored in a 1D array without separation.   Sometimes, it is needed to be read back and rewapted into piece by piece from this 1D array for editing.

[crossrulz]

You could just do two derivatives.  Where the second derivative is not 0 (change in slope), you got an inflection.