[Octave-bug-tracker] [bug #44959] Display coordinates of mouse cursor in QtHandles figures

[Pantxo Diribarne]

Follow-up Comment #16, bug #44959 (project octave):

@Martin: keep in mind that fltk/qt plots are opengl based so they basically
use single precision floats (23 bits mantissa -> ~ 7 digits precision) to
represent data, and 6 digits is not far from the best that we can do. 

Due to the above limitation, it is currently necessary to scale data before
representing them (see bug #32980): for example if you want to represent data
ranging from x = 1e10 to x = 1.0001e10 you should represent (x - 1e10) if you
want it to work as expected. This is an Octave limitation, but not what I
wanted to show :-). Now you have data ranging from 0 to 1e6, but even if you
maximize your figure window, data are represented on a 1000+ pixels screen ...
the actual relative precision of the mouse pointer position is 1/1000 (or
1/3000 if your are rich), *not* 1e-6. Hence having 6 digits is of no use, 3
digits is not enough, 4 digits is the good compromise :-)  


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