[Octave-bug-tracker] [bug #46168] OpenGL use of single causing problems in errorbar

[Rik]

Update of bug #46168 (project octave):

                Category:                Plotting => Plotting with OpenGL   
                 Summary: Bug in errorbar() when X coordinates are near each
other => OpenGL use of single causing problems in errorbar

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Follow-up Comment #1:

I don't think the problem is errorbar.  I think you're running into the fact
that OpenGL uses class single to represent numbers.  If I switch to gnuplot
for plotting, which uses doubles to represent numbers, then the plot looks
alright.


graphics_toolkit gnuplot
x=[2000.59 2000.60 2000.61];
y=[0.00 2.10 -2.70];
ey=[1.36 2.49 2.79];
errorbar(x,y,ey,'.');
print('test_errorbar.pdf','-dpdf');


It's not the fact that the numbers are close together, it's the fact that
you're asking for a precision of .01 / 2000 or 5 parts per million.  An easy
way around this is to scale the numbers.  See below.


x=[2000.59 2000.60 2000.61];
x = x - 2000;
y=[0.00 2.10 -2.70];
ey=[1.36 2.49 2.79];
errorbar(x,y,ey,'.');


If you want the plot to actually read correctly you can change the xticklabel
property on the axis manually.  Assuming the code above,


set (gca, "xtick", [0.59, 0.60, 0.61]);
set (gca, "xticklabel", {"2000.59", "2000.60", "2000.61"});




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