[Gnuplot-info] How to find root or intersection of data plots

[<lyn...@fr...>]

Hello!


Is  there  a  possibility  to  determin  the  root  of  a  data  plot  or  the
intersections of two plots depending on the interpolation type that was chosen
for plotting? Is that possible with gnuplot or another free linux tool?
I know it is tricky to define the intersection points for data plots since the
intersection mostly depends on the interpolation type and is rarly exactly  on
a  data  point.  Still it is often necessary to estimate the intersection of a
data plot with another or with a function.
It would be already helpful to know the two data points in between  which  the
intersection  would  lie.  I  guess  for  the  problem  of  finding  the  root
(intersection of a plot with the x-axis) it would just be a problem of finding
the pairs of adjacent points where thy y-value chages sign.
Any  way to  do that with gnuplot or another tool? Still, having an evaluation
possibility depending on the gnuplot interpolation type (eg.  straigth  lines,
splines or kdensity) would be great.

Thanks for any help or hints about this.
Lynx