Weird vertical lines with plot function

Dear all,

While trying to plot a specific dataset, I encouter a weird behavior:

load elpenon
figure; scatter(elpenon(:,1)*1000,elpenon(:,3),10,'k')

gives the appropriate plot

However, when calling :

figure; plot(elpenon(:,1)*1000,elpenon(:,3))

Warning: Graphics acceleration hardware is unavailable. Graphics quality and performance might be diminished. See MATLAB System Requirements.

I obtain this :

These weird vertical lines appears. No data support this as shown in the scatter plot.

max(elpenon(:,3))=-1.3800

so nothing above 0 but stil shown in the plot

changing linejoin properties does not solve the issue. The plot although is correct when setting linewidth to .1.

When using the pan tool in the figure window to move the plot around, the vertical lines diseappear when the origin of the extra line is outside of the x and y lims.

Can anyone explain this and propose a workaround?

Thanks

[Stephen23]

What OS ?

version

ans = '26.1.0.3203278 (R2026a)'

S = load('elpenon.mat')

S = struct with fields:
    elpenon: [3594×3 double]

M = S.elpenon

M = 3594×3

12.0700 0 -4.5500 12.1100 0.4000 -3.5100 12.1600 0.8000 -4.0400 12.2000 1.2000 -4.6700 12.2500 1.6000 -4.9600 12.2900 2.0000 -5.3800 12.3400 2.4000 -5.0600 12.3800 2.8000 -5.3200 12.4300 3.2000 -5.3900 12.5200 4.0000 -5.3000 12.5600 4.4000 -5.1700 12.6100 4.8000 -5.3100 12.6500 5.2000 -5.5400 12.7000 5.6000 -5.4400 12.7400 6.0000 -5.6800

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scatter(M(:,1)*1000,M(:,3),10,'k')

plot(M(:,1)*1000,M(:,3))

[Olivier]

Dear Stephen23

MacOS Tahoe V 26.4.1

[Walter Roberson]

Datapoint:

I obtain normal plots with R2025b on MacOS Intel Tahoe 26.5

[Olivier]

I updated both matlab and OS and still have the same result.

Could it come from some settings?

[Torsten]

Contact support:

https://uk.mathworks.com/support/contact_us.html

They can open a remote session on your computer and have a better chance to find what the problem is.

Do you have an Apple Silicon Mac or an Intel-based Mac ?

[Olivier]

Apple silicon.

It may be or not related but I now have weird lines within contour plot that used to work fine in a previous laptop.

I will try the support! Thanks for your help

[Olivier]

Also, I realized that this happens when I have in the data several consecutive lines with a single x value but different y value.

[Torsten]

@Olivier

Include a link to this question in your support request. Then you don't need to supply all the material twice.