gnuplot-info

[Gnuplot-info] fit a data file

[laura <lau...@ho...>]

Hello,
I want to fit a curve to data using the least square method.
I have try to do the next but doesn't work:
fit 'datafile.dat', y=a*x+b, via a,b
My data see thas:
                          *
                       *
                    *
                 *
              *
           *


What can i do? Thank you very much.

Re: [Gnuplot-info] fit a data file

[<als...@ma...>]

Quoting laura <lau...@ho...>:

> Hello,
> I want to fit a curve to data using the least square method.
> I have try to do the next but doesn't work:
> fit 'datafile.dat', y=a*x+b, via a,b
> My data see thas:
>                          *
>                       *
>                    *
>                 *
>              *
>           *
>
>
> What can i do? Thank you very much.
You need to this:
1.first define the function you want to fit with: by
f(x)=a*x+b

2.let us say that your xdata values are in column 2 in datafile.dat, 
and your ydata values are in column 4 then your fitting command should 
read:
fit f(x) 'datafile.dat' u 2:4 via a,b

that's it
if you need more info consult the documentary of gnuplot by :
help fit

Ramzi Alsallaq
Florida State University




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Re: [Gnuplot-info] fit a data file

[<HBB...@t-...>]

laura wrote:

> I want to fit a curve to data using the least square method.
> I have try to do the next but doesn't work:
> fit 'datafile.dat', y=a*x+b, via a,b

Things like that happen if you don't read the documentation carefully. 
The command you're looking for is

	fit a*x+b 'datafile.dat' via a, b