I have a function f(x) = a/x
and I have a set of data containing values for f(x) +- df(x)
and x +- dx
. How do I tell gnuplot to do a weighted fit for a
with that?
I know that fit
accepts the using
term and this works for df(x)
, but it does not work for dx
. It seems gnuplot treats the error I have for x
as the error for the whole RHS of my function (a/x +- dx
).
How do I do a weighted fit that fits f(x) +- df(x) = a/(x +- dx)
to find the optimal a
?
Since version 5.0, gnuplot has an explicit provision for taking uncertainty in the independent variable into account
fit f(x) datafile using 1:2:3:4 xyerror
using "Orear's effective variance method".
(Above command expects data in the form x y dx dy
.)