How to do a fit with gnuplot using data with error in x and y?

gnuplot data-fitting
physnolimits picture physnolimits · Sep 5, 2015 · Viewed 17k times · Source

How to do a fit with data like x y deltax delta y? I have to do a linear fit weighted to the error in both axis what is the exact syntax?

Fit f (x) "file.txt" u1:2:3:4 via a, b with xyerrorbars.

f (x) =a*x + b

Result: singular matrix in invert_RtR

Answer

Christoph picture Christoph · Sep 5, 2015

To fit with x and y errors you need gnuplot 5. Then use the syntax

f(x) = a*x + b
fit f(x) "file.txt" using 1:2:3:4 xyerrors via a,b

See the last example on http://gnuplot.sourceforge.net/demo_5.0/fit.html for a full demo.

Related questions

gnuplot - Does `set xrange [x_min:x_max]` limit the ranged used for function fit?

Simple question - the range drawn on a plot can be changed with the set xrange [x_min:x_max] command. Does this command also limit the range used when fitting a function using the data fitting tools in gnuplot? …

Read More
fit a function to a histogram created with frequency in gnuplot

Intro In gnuplot there's a solution to create histogram from file named hist.dat what likes 1 2 2 2 3 by using commands binwidth=1 set boxwidth binwidth bin(x,width)=width*floor(x/width) + binwidth/2.0 plot [0:5][0:*] "hist.dat" u (bin($1,binwidth)):(1.0) smooth freq with …

Read More
How can i reduce the linear fit plot to a certain interval?

what i do is to fit two linear function´s to my data. i know how to select the data for the various fitting functions. My problem is that i want the fitted lines only to be plottet in a …

Read More