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Groups > comp.graphics.apps.gnuplot > #3487

Re: linear fit of looped (and cutted) data set

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Am 27.11.2016 um 16:31 schrieb Markus Grünwald:
> I've done measurements of cycling loads and saved into a text-file. Now i need to make a linear fit to these data points by only take care of a specific part of data points (limited y-range). - Hard to descirbe - therefore i tried to make a sketch of it: see http://ovh.to/2u45XF4
> 
> If i'll do this by setting a set of range during fit-command by using:
> [code]
> f(x) = k*x + d
> fit [x_min:x_max] [y_min:y_max] f(x) "DATA.txt" using 2:3 via k,d
> [/code]
> i'll get a wrong fitting curve, because gnuplot seams to connect the dead ends of the cutted Data-set (seen in (1) of my sketch).
> 
> I think i will need a function that fits the linear function best to existing points ignoring the cutted dead ends (seen in (2) of my sketch).


Note that the order of datapoints makes no difference to the fitting
algorithm. It only sees a cloud of pairs of xy values.

And each section of your curve has its own intersect d.

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linear fit of looped (and cutted) data set Markus Grünwald <m_grueni@web.de> - 2016-11-27 07:31 -0800
  Re: linear fit of looped (and cutted) data set Ethan A Merritt <EAMerritt@gmail.com> - 2016-11-27 11:29 -0800
    Re: linear fit of looped (and cutted) data set Markus Grünwald <m_grueni@web.de> - 2016-11-27 14:56 -0800
      Re: linear fit of looped (and cutted) data set [solved] Markus Grünwald <m_grueni@web.de> - 2016-12-26 14:52 -0800
  Re: linear fit of looped (and cutted) data set Karl Ratzsch <mail.kfr@gmx.net> - 2016-11-27 22:11 +0100

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