[Libreoffice-bugs] [Bug 43983] Explanation how chart Automatic axis scaling works required (see comment 5)

[bugzilla-daemon at bugs.documentfoundation.org]

https://bugs.documentfoundation.org/show_bug.cgi?id=43983

--- Comment #15 from matthewnote at yahoo.co.uk ---
"For a start Value 10 it's a benefit to see the distance of the line from Y=0,
most users can live with the white area below the curve (and to avoid it, you
can scale Y-axis manually)"

Here I'm providing an engineering analysis of medical evidence of disease
proliferation (Y axis) due to logarithmic values of cause (X axis) and the
autoscale is a huge problem.   I think the Bug is raised because nobody helped
the Libreoffice team at the start with X,Y scatter reality.  To show the
problem, creating two columns with row values the same, starting 75 to 150. 
Plot the columns as X,Y scatter.  The X values are trimmed to autoscale, the Y
axis still includes zero.   The difficulty is else than "most users" or "can
live with it".   The line of points is expected to pass through the autoscale
origin (both axes treated equally the same, of equal interest).  In engineering
or mathematics, the work is without interest nor knowing if X causes Y or
perhaps Y causes X.   That mental habit exists (due to histogram presentations)
and often persists due to using X axis for "time" values.  However, in reality
of work - the scale depends on the area of interest.  Autoscale zoom is very
important.   In analysis or drawing office work you spend years learning how to
do it by hand.  It's tough to find the computer won't.

Well, in the spreadsheet I'm providing, LibreOffice is excellent and solid,
very stable.  However, twelve sheets with three graphics each, plotting 20000
points each, using 600 trend lines is pushing a Kaby Lake processor to it's
limits.  Rescaling all charts at any choice of data change (global factors are
necessary to analyse) has become impossible.   The charts are great, the
workload to adjust is untenable (about two hours labour to adjust all graphics
Y axes - every time one digit is changed). I'm a bit stuck.

To provide the user with the possibility to stretch out the autoscale "zoom", I
provide each graphic with a cursor (one x value/coordinate, one y
value/coordinate) set by the user.  Furthermore, all points with invalid x or y
values are shoved under that cursor (using ERRORTYPE) so that trend lines do
else than chaos.   It works, yet two thirds of every graphic is empty and the
information (the variations) are squashed so hard on the Y axis as to be
unreadable.   I use and ask medical staff to use a 4K monitor, yet still it's
tough.   Workaround:  As well as the User Cursor cells, the spreadsheet here
now offers a Y axis offset value.   When the user puts (for example) -100, the
Y axis autoscale detects '0' is now crossed by some of the data and bingo, it
snaps into useful presentation mode.   The user can still stretch out the
window using the cursor. That is else than to please:  the variations often do
have a tendency and stretching out to where that is makes sense of everything. 
It's rarely (if ever) toward y=0.  that's a histogram thought.

(To make sure the user remembers he's altered the raw data, there's a very
large white-on-black cell group that announces a warning about the offset and
what it actually is.  It's the best I can do without macros).

It's understandable that placing a bug note about this might disturb, because
the software works and the philosophy usually seems open to debate, yet in hard
factual terms, favouring x or y axis (and not the other) as the only reference
to be autoscaled is quite . . . . . .well, wrong.  (I know that's an awful
word).

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