On Sunday, April 14, 2019 at 6:56:16 PM UTC+2, Karl Ratzsch wrote:

Am 14.04.2019 um 17:19 schrieb hugocoolens@gmail.com:

I am puzzled by the following discrepancy between a stats command result and the result which I have from normal Gnuplot fitting:

f(x)=a*log10(x)+b

a=-1.06

b=-4.78

fit [3e-3:1] f(x) datafile using ($1):($2) via a,b

stats [3e-3:1] datafile using (log10($1)):($2)

The Gnuplot fitting gives me y=ax+b, with the correct a=-1.16816 and b=-4.78604

But the stats-command gives: y = -3.104 x - 4.194

Not problem with fit or stats, your range setting for stats was

wrong: you have to logarithmise it as well

stats [log10(3e-3):log10(1)] $dat using (log10($1)):($2)

and the linear model that comes out is y = -1.168 x - 4.786

;-)

Thanks a lot!

kind regards,

Hugo

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