Re: Changes to gnuplot fitting submitted to sourceforge as patch

[Thomas M. <mat...@ph...>]

On 10-Mar-06, at 10:45 AM, Bastian Maerkisch wrote:

>
> Personally I would prefer new options to `set fit` instead of dozens 
> of new
> FIT_xxx variables. This would be more consistent with setting other
> options in gnuplot.

Controlling things through a "set fit" mechanism rather than FIT_xxx
is an appealing idea, I wish I had thought of it.  It makes controlling
fits more like controlling other things in gnuplot.  Certainly for
_new_ controls where there is no back-compatibility issue it sounds
better than more FIT_xxx clutter in the namespace.  I just copied the
code in fit.c which didn't use set, because that was easier.  I'll
look at your patch to learn how to use set and make an alternative 
patch.

Perhaps we could also have "set fit xxx" control things presently
controlled via FIT_xxx, then slowly deprecate FIT_xxx.  We'd have
to have a rule for how to resolve conflicts if both mechanisms were
trying to control things at the same time.  The simplest is just to
let the most recent change apply, and change both the set/show state
and the FIT_xxx state.  It would then be nice to issue a warning if
the value is set with one mechanism then changed using the other
mechanism, since that is more likely to be a mistake than changing
the value many times through the same mechanism.  I don't know if
dual-control would be easy or hard, I haven't looked at the 
implementations.

I'd also like to make the fit_command parser accept the same syntax
for errors that the plot command does, for further consistency 
improvement.
But that's not my highest priority.

> Attached you find an extension to gnuplot's fit which I have been using
> for a while. It adds the possibility to turn off error scaling via
> `set fit errorscaling` and saving of fit information (chisq, dof, WSSR)
> to user variables as requested by Hans Boie (SF #1117724 [fit] access
> to resulting chisquare) via `set fit fitvariables`. It also fixes
> (SF #1324672 ] doc: false reference to "set fit").
>

Having a switch like this may be the only way to get me and Hans-
Bernhard to stop going back and forth about it ;-)

And having variables for chisq, etc turned on by GP_FIT_ERRVARS
switch is probably a good idea (although then we'd have to agree on 
names.. ;-)

> These are just tiny modifications and could probably be integrated
> into this large and very nice patch.
>
> Bastian
>

It's nice to be appreciated!