gnuplot - get errors on fit parameters, get fit output values as variables, print variable to screen

Question

Initial Question (Partially Answered)

I am using gnuplot's fitting routines to fit a function to some data, and extract a "characteristic decay time constant". (I call this parameter d in my fitting function.)

I have used the script code set fit quiet to prevent reams of text being printed to the terminal. However I now have no way of knowing what the final fit values were! (Except by inspecting the log file... which is arduous...)

Is there a way I can get the final fit parameter values back, store them in a variable, and print that variable?

I guess this is 2 questions in one... How do I print a variables value?

Answer to Initial Question

So after some playing around with gnuplot, I have found that the print command can print variables to screen, and that the parameters, eg d are already available for use as variables - ie; they are already variables.

So I can do the following: print "d=",d - the comma here is used to separate things you want to print. So I first print a string "d=" followed by the value of d.

Next Question

How do I obtain the errors on the variables I have used? Eg; if I fit a function with parameters a,b and c, how can I print the errors on these values?

Answer 1

Quoting the documentation:

If activated by using set fit errorvariables, the error for each fitted parameter will be stored in a variable named like the parameter, but with "_err" appended.