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I have data points from a power spectrum (fft) output that look like the image below.

A characteristic of the data seems to be a heavy slope and then a flattening out. I would like to be able to calculate the slope of the line approximating the steep slope section (shown in blue) and the point at which it "kicks out" and starts flattening out (the corner of the blue angle).

How can this be done?

thanks in advance.

additional info:

  • The different sets have different slopes results in different kick-out points. so I can't just run best fit line on a fixed segment of the data.

Power Spectrum

share|improve this question
    
Quite related... –  J. M. Dec 14 '11 at 23:54
    
Thanks, that is quite related. Was hoping for an easier implementation. Least I know it's called piecewise continuous linear :) –  MandoMando Dec 21 '11 at 19:23
    
Is the plot on a log-log scale? –  Tpofofn Mar 28 '12 at 0:49
    
@Tpofofn the graph is linear scale. –  MandoMando Mar 28 '12 at 18:26

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