How can I reduce the linear fit schedule to a specific interval?

Question

what i am doing is matching two linear functions for my data. I know how to select data for various fitting functions. My problem is that I want the set lines to be just a plot in a certain amount of time. What i have done so far:

f(x) = a*x + b; fit [800:1250][-2:8] f(x) 'Daten.txt' u 1:2 via a,bg(x) = c*x + d; fit [1258:1650][-2:8] g(x) 'Daten.txt' u 1:2 via c,d plot "Daten.txt" u 1:2 wl, f(x) t title_f(a,b), g(x) t title_g(c,d) 

This leads to

image that I am not allowed to publish ...

How can I make a green fittin line just for starting from 800-1200 and a blue fitting line from 1100-end?

Answer 1

Syntax

 plot [xmin:xmax] f(x) 

(same as fit ) limits the graph to a certain range. So you can do something like

 plot "Daten.txt" u 1:2 wl, [800:1200] f(x) t title_f(a,b), [1100:] g(x) t title_g(c,d)