gnuplot-info

[Gnuplot-info] Any suggestion for better fit function?

[smms <sm...@ho...>]

I know it is rather a "do-it-for-me" post but thought someone could help me
with a better fit suggestion. 

Here is my data set I managed to fit (not quite exciting) with following
scripts and function. Just looking for if someone could suggest a better
function. Many thanks for any feedback.

reset
set key bottom right
f(x) = a*atan(x/b); a = 2.65; b = 2.5 
fit f(x) 'test.dat' u 4:25 via a,b
plot 'test.dat' u 4:25 w p not '0.99-3%-1200', f(x) t 'f(x)'


test.dat data set is here,

2.561	2.642
0.686	2.685
0.586	2.647
0.487	2.658
0.402	2.620
0.284	2.516
0.213	2.440
0.197	2.359

Here is my fitted plot,

<http://gnuplot.10905.n7.nabble.com/file/n17899/test.bmp> 




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Re: [Gnuplot-info] Any suggestion for better fit function?

[Dr. I. D. J. <die...@t-...>]

Well,
kind' of "did-it-for-you" ... :-)

What about g(x)=a*x/(1.0+b*x)*exp(c*x)

through

fit g(x) "test.dat" via a,b,c

results here in 
a=68.4844227089402
b=23.4451718533986
c=-0.0329804676514508

and the fit seems quite acceptable (for me ...)

HTH,
take care




Dieter Jurzitza

On Donnerstag, 2. Januar 2014 23:16:05 smms wrote:
> I know it is rather a "do-it-for-me" post but thought someone could help me
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Re: [Gnuplot-info] Any suggestion for better fit function?

[smms <sm...@ho...>]

Many thanks Dietar for sparing your time for me. 
Eventually I managed to fit with g(x) = a*atan(x/b).



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