gnuplot-info

[Gnuplot-info] fitting function

[Sabari <sa...@gm...>]

Dear All
What is the difference between  "using 1:2:3 and using 1:2:3:(1)" for 2d fit

for example

fit f(x,y) "nor.dat" using 1:2:3 via a,b,c
fit f(x,y) "nor.dat" using 1:2:3:(1)  via a,b,c

with thanks and regards

sabarinathan.v

Re: [Gnuplot-info] fitting function

[Thomas S. <t.s...@fz...>]

'using 1:2:3' means 'using x:z:s', so you omit the y-values.
see the help information of gnuplot or
http://www.gnuplot.info/docs/gnuplot.html#x1-9400057

'using 1:2:3:(1)' is the right syntax.


sabari wrote:
> 
> Dear All
> What is the difference between  "using 1:2:3 and using 1:2:3:(1)" for 2d
> fit
> 
> for example
> 
> fit f(x,y) "nor.dat" using 1:2:3 via a,b,c
> fit f(x,y) "nor.dat" using 1:2:3:(1)  via a,b,c
> 
> with thanks and regards
> 
> sabarinathan.v
> ------------------------------------------------------------------------------
> _______________________________________________
> gnuplot-info mailing list
> gnu...@li...
> https://lists.sourceforge.net/lists/listinfo/gnuplot-info
> 
> 

-- 
View this message in context: http://old.nabble.com/fitting-function-tp28387212p28390571.html
Sent from the Gnuplot - User mailing list archive at Nabble.com.

Re: [Gnuplot-info] fitting function

[Hans-Bernhard B. <HBB...@t-...>]

Sabari wrote:

> What is the difference between  "using 1:2:3 and using 1:2:3:(1)" for 2d fit

Primarily that one of them is _not_ a 2D fit.  Which of those that is 
depends on what exactly you mean by "2D" fit.

> fit f(x,y) "nor.dat" using 1:2:3 via a,b,c

This won't work.  A fit with 2 independent variables needs four using 
specifications: x, y, z and delta_z.  If your data file lacks a delta_z 
column, you have to invent one, like that:

> fit f(x,y) "nor.dat" using 1:2:3:(1)  via a,b,c

And since all of this is described right on the first page of "help 
fit", I really wonder how you managed to miss this.