Morten Welinder wrote:
> Yes, a chain saw can be dangerous but it is fundamentally a good tool
> when used right.
>
My mother's uncle, who had been totally blind since the age of two,
actually
bought a chainsaw to use for cutting firewood. He only lost one of his
fingers.
_
Use of the condition number is sensible. If one can detect polynomial
regression, however, there are alternatives that may improve the
condition, and it would be nice to tell folk. That's not necessarily
Gnumeric's job, of course. And there may be more important "bad habits"
that should be deal
Unfortunately we cannot really know if the user's use of the tool is sane.
Yes, a chain saw can be dangerous but it is fundamentally a good tool
when used right.
What we can do -- at least for the GUI regression tool -- is to check the
condition number of the relevant matrix. We do that already a
The type of dialog Adrian suggests would be a very sensible feature.
Sometimes one really does need to do the polynomial regression, even if
to show the issues, so it is not right to completely bar an approach.
However, when we have an interested person, it's a good opportunity to
point them to
Lovely repartee, just the sophisticated answer that gnumeric brings to
the spreadsheet world.
Any chance you can craft this into a good popup dialog? e.g.
You are trying to use SOME_METHOD which exists in gnumeric only
to allow compatibility with other older spreadsheet programs.
Polynomial regression was where I came into numerical analysis at the
beginning of my academic career 40 years ago. It is a dangerously
ill-conditioned problem, meaning that the regression parameters are
untrustworthy, though the "fit", i.e., the model, may be useful if the
calculations are don