[Gnuplot-bugs] Inconsistency in splot to table / splot binary data

[Juergen P. <pr...@ma...>]

  Dear gnuplot developers,

encouraged by the manual to report bugs in the gnuplot program, I want to
address today a kind of an inconsistency present in gnuplot version 4.0, but
to my knowledge it exists at least already in version 3.7.
The inconsistency is related to the role of x and y in ordered grid data,
produced by output to the table terminal, best seen when hidden3d option
is set:

1) splotting data files that are ordered like explained in sect. 38.1.2
   "Example Datafile" in the gnuplot 4.0 manual (i.e., ordered in data
   blocks with constant x value and varying y values) works fine: O.K.
   (first plot in my demo file)
2) splotting functions in x and y works fine, O.K. (second plot in demo)
3) splotting functions in x and y to terminal "table", saved into a file,
   and subsequent splotting of the resulting grid data in that file works,
   but not completely as one expects it: (third plot in demo).
   In the data blocks of the generated file y is held constant, and x
   varies. Consequently, the plot is drawn "inside-out", as promised in
   sect. 38.1.2 of the manual.

Although this surely is no "bug" in a narrow sense, but I think it is not
as it should be, and may be sometimes annoying, at least irritating.

A phenomenon that may be related to this is probably a bug, otherwise an
error in the manual:

4) splotting binary data written as specified in sect. 38.1.1 results in
   both: interchanged x and y *meaning* and a plot with "inside-out" color
   choice. (Fourth plot in demo, provided your system uses IEEE
   representation of floats with big endians).
5) Both errors can be healed at once when plotting with "using 2:1:3"
   specifier: (fifth plot in demo). This may be a hint to the error.


Provided files (attached to this e-mail):
"xy_mixup.gpl":     gnuplot macro file for demonstration
"xy_griddata.gba":  ASCII griddata with correct specification
"xy_mixup.gba":     ASCII table data from gnuplot, generated by macro
"xy_mixup_bin.gbb": binary griddata file
                    (IEEE, big endian, generated on Intel PC)
"xy_mixup_bin.c":   C source for generating the binary griddata file

My system: MS-Windows 32 bit, or CYGWIN-NT 5.0 (X11)

Best regards,
               J. Prahl.