## gnuplot-info

 [Gnuplot-info] [Non linear regression] How to store the standard uncertainty of a parameter in a variable ? From: David Kremer - 2011-10-03 09:10:01 ```Hello, I often use GNUplot to make regression using the "fit" function because I find it useful and somehow easy to use. Since you define the parameters as variables before to launch the fit, you can then print out the values of the parameters you obtained after the fit. My question is : how can you do the same with uncertainty errors ? When you do a fit, if everything goes fine, you should end up with some lines like : After 3 iterations the fit converged. final sum of squares of residuals : 7.15422 rel. change during last iteration : -2.85539e-15 degrees of freedom (FIT_NDF) : 898 rms of residuals (FIT_STDFIT) = sqrt(WSSR/ndf) : 0.0892571 variance of residuals (reduced chisquare) = WSSR/ndf : 0.00796684 Final set of parameters Asymptotic Standard Error ======================= ========================== BG = 0.141662 +/- 0.002977 (2.101%) My question would be, how to catch the number the asymptotic standard error (that is to say the number 0.002977) in a var, to be able then to print this number out. Thank you very much. David ```
 Re: [Gnuplot-info] [Non linear regression] How to store the standard uncertainty of a parameter in a variable ? From: Thomas Sefzick - 2011-10-03 09:41:43 ```David Kremer gmail.com> writes: > ... > When you do a fit, if everything goes fine, you should end up with some > lines like : > ... > > Final set of parameters Asymptotic Standard Error > ======================= ========================== > > BG = 0.141662 +/- 0.002977 (2.101%) > > My question would be, how to catch the number the asymptotic standard > error (that is to say the number 0.002977) in a var, to be able then to > print this number out. "set fit errorvariables" then do the fit and look for "_err" in "show variables all" (here: BG_err) and print the variable. ```