[bug #68154] Viewing the value of time (x axe) of each point of a 2-D plot

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URL:
  <https://savannah.gnu.org/bugs/?68154>

                 Summary: Viewing the value of time (x axe) of each point of a
2-D plot
                   Group: GNU Octave
               Submitter: michelangelo
               Submitted: Mon 16 Mar 2026 03:29:13 PM UTC
                Category: Plotting
                Severity: 3 - Normal
                Priority: 5 - Normal
              Item Group: Feature Request
                  Status: None
             Assigned to: None
         Originator Name:
        Originator Email:
             Open/Closed: Open
         Discussion Lock: Unlocked
                 Release: 10.1.0
        Operating System: Microsoft Windows
           Fixed Release: None
         Planned Release: None


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Follow-up Comments:


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Date: Mon 16 Mar 2026 03:29:13 PM UTC By: Michelangelo <michelangelo>
I'm doing post-processing of signals coming from an oscilloscope (electrical
signals). These signals are sampled at 2.5Gbps, so they has a time
discretization of 4e-10. I have the waveforms as csv files, with all the
digits needed for a so high frequency sampled signals. x coordinate is the
time, y is the voltage at that time. I need a so high sample frequency for
frequency related measure, like rise time of fast digital signals.

When I plot the csv files on Octave v10.1.0, I can see in the graph all the x
y coordinates by hovering the mouse on a specific point. But I see that, even
if I zoom the graph a lot to see the sigle samples during time, the x
coordinate (the time) doesn't change for many consecutive samples, becouse of
the rounding of the viwer. For sure, the original precision was preserved
inside Octave: if that's not true, you can't see the waveform in the correct
way. Also, if I do the difference between two consecutive x coordinates,
addressing the x vector that I use for the plot, I get 4e-10, and not 0.
I try the ginput() function, but when I click on the plot point that I want to
measure, it returns on the Octave console the same precision that I see before
on the plot window.

For sure, I can do an algorithm that calculate the rise and fall time of
signals: doing this on the code, I will get the right precision. But in
general, I want to see on the graph also the right precision at least for each
sample point that are plotted. So I can make some fast conclusion about the
signal, even without implement the full algorithm (or to verify manually and
visually if an  algorithm is working well)







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