Re: Undocumented behaviour of "smooth" options

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

Am 22.02.2017 um 00:21 schrieb Ethan A Merritt:

> On the bug tracker    <https://sourceforge.net/p/gnuplot/bugs/1911/>
> Rainald Koch points out that when a data set contains some points with
> invalid y values, the result of smoothing is unexpected.

Expectations can be deceiving.  :-)

> I can't find any mention of it in the documentation, but it seems that
> this is intentional.  The "smooth" code has a pre-processing step that
> splits the input data into N subsets separated by one or more "undefined"
> points.

Well, what else was the code to do with actual blank lines in the input, 
or otherwise missing/unusable data?  And back in the day, invalid data 
_was_ often treated as being the same thing as missing data.  Plotting a 
spline across a hole in its input data would IMHO be at least as wrong 
as the lack of documentation of the current behaviour.

The behaviour of the smoothing code is not that wildly different from 
that of the normal 'with lines' behaviour, really: a missing entry 
breaks the polyline, so it's not entirely unepected that it breaks the 
smoothed curve, too.