Re: fit ignores yrange

[Ethan A M. <sf...@us...>]

On Friday, 05 June, 2015 23:07:19 Hans-Bernhard Bröker wrote:
> Am 05.06.2015 um 22:49 schrieb Ethan A Merritt:
> 
> > I don't know what the intent was with regard to adding in-line
> > range restrictions in the "fit" command.
> 
> The intent should be obvious: 'fit' should accept the same data input 
> options as 'plot'.  That's what the documentation always said, and it's 
> what the code did until two years ago, and almost did even after that 
> change.
> 
> Overriding 'set' options on-the-fly has been possible in gnuplot since 
> day one, and 'fit' was no exception to that, nor should it be.
> 
> 'fit' actually still did honor a yrange ... but only in a fit with more 
> than one independent variable.  The yrange was ignored only if there was 
> one variable, but two range specifications.

Exactly.  

'fit' is treating y as the name of an independent variable, not
as the name of the result f(x).  The question is whether the
intent was to allow
   fit [xmin:xmax][zmin:zmax]  f(x) 'data'
even though the plot command, the documentation, and the
current fit command all treat the second bracketed range
as a restriction on y rather than on z.

Alternatively the intent of 
  "f(x, y, ...) = z  even for the case f(x) = z" 
might have been to allow
   fit [xmin:xmax][][zmin:zmax] f(x) 'data'

I.e. a range restriction on z requires 3 bracketed pairs
even if there is no 'y'.

Neither of these works at the moment, but which would
cause the least confusion?

	Ethan