Error in the plot function/low resolution

2021 2 5
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更新时间：2021 2 9
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Hi everyone!
I have an EMG signal at 1000Hz. When I use the plot(EMG signal), the x values only move at 10 ms (anything inside this gets the same x value), the y values are working fine (upper pic). If I cut the signal to a smaller piece, the error is gone (lower pic). I need the 1ms resolution to define events.

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Pedro Valadao
Pedro Valadao 2021-2-9

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Hi all,
It is not an error. It is just the precision of the datatip function. It is easily adjustable on the following line:
formattedValue = [valueFormat num2str(value,4) removeValueFormat];
i found this info on the following discussion:
https://www.mathworks.com/matlabcentral/answers/288287-how-to-increase-the-range-of-measurement-of-data-cursor-in-a-plot
Cheers!
Pedro.

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Hi, it is hard to find (and fully understand) your problem without having your code.
If I understand your question right, you want to be your upper plot in a better resolution. Since you have the data probably available in a better resolution (second plot), I would guess that some function deletes some values on the way, it could be for example the function linspace(x1,x2,resolution) which does this to your data.
Pedro Valadao
Pedro Valadao 2021-2-5

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Hi Max,
Thank you for the quick reply! The same error occurs with the following code:
v = rand(1,150000),plot(v) % here the error happens as in the upper figure
figure, plot v(1:200) % here the error does not happen as in the lower figure
I have checked multiple files with the same type of data, .mlx and .m - the same problem happens consistently.
Br, P.

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That should not be the case. As far as i know, MATLAB does not shorten your data you plot in a visible way, which often causes speed problems because people plot more data than they should do.
If I run the code you sent I cannot see any difference in the resolution. When I zoom in the right plot the displayed data is the same as in the left plot
Maybe some different MATLAB IDE causes that? Do you juse the appdesigner, a life skript or MATLAB online?
Pedro Valadao
Pedro Valadao 2021-2-5
Hi, I'm using matlab R2020a installed on my pc.
v = rand(1,150000)
figure, subplot(2,1,1), plot(v), subplot(2,1,2), plot(v(1:200))
If I zoom both a lot and use the data tips, the following happens:
Pedro Valadao
Pedro Valadao 2021-2-8
Hi @Star Strider,
sorry if this is too much of a newby question, I'm tagging you because you have answered pretty much all questions I have seen in this forum! haha
Could you please help?
Br, Pedro.

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