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Re: Intersection point of data-plot and linear-function

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Am Dienstag, 27. Dezember 2016 11:02:35 UTC+1 schrieb Karl Ratzsch:
> Am 27.12.2016 um 00:13 schrieb Markus Grünwald:
> > Just to be sure (because i need the same thing - and maybe there were lot of improvements till this last post):
> > There is no way in gnuplot to get the intersection point of a data-set (or a smoothed spline of it) with a linear function (y=k*x+d)?
> > 
> 
> No. At least no simple, straightforward way. Remember gnuplot is a
> plotting tool, not a data evaluation suite.
i suspected that - wanted just ask to be sure (thanks for quick response)

> If you can model your data by some analytical function(s) that you
> can fit, then you could derive the intersection, and use "set label
> point" to mark it.
i decided to make a linear fit at a short range where the intersection is estimated - with a few iterative runs i'll get a quite good approximation:

[code]
F_max_x=###
g1(x) = k1*x + d1
g2(x) = k2*x + d2
k1=###; d1=###
fit [F_max_x-0.25:F_max_x+0.25] g2(x) "DATA.txt" using 1:2 via k2,d2
F_max_x=(d2-d1)/(k1-k2); F_max=k1*F_max_x+d1
[/code]

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Intersection point of data-plot and linear-function Markus Grünwald <m_grueni@web.de> - 2016-12-26 15:13 -0800
  Re: Intersection point of data-plot and linear-function Karl Ratzsch <mail.kfr@gmx.net> - 2016-12-27 11:02 +0100
    Re: Intersection point of data-plot and linear-function Markus Grünwald <m_grueni@web.de> - 2016-12-28 15:43 -0800

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