gnuplot 5.0 in xubuntu 16.04.2

[Jiri Nerad]

Dear developers,

The gnuplot package included in xubuntu 16.04.2 has incomplete functionality of handling missing data points
(while gnuplot in xubuntu 14 worked slightly differently - and correctly).

gnuplot package version reported by aptitude is 4.6.6-3.
However, when launched, gnuplot says it is "version 5.0 patchlevel 3, last modified 2016-02-21".

The handling of missing data points changed between gnuplot 4 and 5.

Official gnuplot 5 documentation (http://www.gnuplot.info/docs_5.0/gnuplot.pdf) says the options should be:

set datafile missing "<string>"
set datafile missing NaN
show datafile missing
unset datafile

However, when I call gnuplot from xubuntu 16.04.2, its help command only lists the following possibilities:

set datafile missing "<string>"
show datafile missing
unset datafile

Alghough it claims it is gnuplot 5, it does not include the second option (set datafile missing NaN),
and when I try this syntax I get an error.
So I cannot instruct gnuplot to treat all entries that do not evaluate to a valid number as missing data.

To make things even worse, the available syntax does not seem to work correctly.
For instance
set datafile missing "nan"
does not work as documented, string "nan" (without quotes) in the data file is understood as error,
not missing data, and I get gaps in my lines.

Looks like the datafile missing feature is not fully implemented in the gnuplot package presently included in xubuntu 16.04.2,
or rather, the change of functionality between gnuplot 4 and gnuplot 5 is not fully implemented and does not work as documented.

Best,
Jiri

================================================================
Aptitude output:

Package: gnuplot                         
State: installed
Automatically installed: no
Version: 4.6.6-3
Priority: optional
Section: universe/math
Maintainer: Ubuntu Developers <ubuntu-devel-discuss at lists.ubuntu.com>
Architecture: all
Uncompressed Size: 33.8 k
Depends: gnuplot5-qt | gnuplot5-x11 | gnuplot5-nox
Suggests: feedgnuplot, gnuplot-doc, libgnuplot-iostream-dev, python-gnuplot
Provided by: gnuplot5 (5.0.3+dfsg2-1)
Description: Command-line driven interactive plotting program
 Gnuplot is a portable command-line driven interactive data and function plotting utility that supports lots of output formats,
 including drivers for many printers, (La)TeX, (x)fig, Postscript, and so on. The X11-output is packaged in gnuplot-x11. 

================================================================
Gnuplot output:

G N U P L O T
Version 5.0 patchlevel 3    last modified 2016-02-21 

Copyright (C) 1986-1993, 1998, 2004, 2007-2016
Thomas Williams, Colin Kelley and many others

================================================================