Problem with stem()?

Hi,

I am using the stem() function to plot some DT signals. The problem I am facing is that stem line is not following the colour of the marker. When I force a colour change using 'b' or 'r' (for example) only the marker changes but the stem line stays as is. Please refer to the figure & code bellow. I am using MATLAB R2018a.

Thanks!

figure(1);
subplot(2, 1, 1);
stem(t1, x400_n, 'b');
title('x400[n] @ fs = 400Hz');
xlabel('n');
ylabel('x[n]');
grid on;
subplot(2, 1, 2);
stem(t1, x400_n_1stHarm, 'b');
title('1st harmonic of x400[n] @ fs = 400Hz');
xlabel('n');
ylabel('x[n]');
grid on;

[Guillaume]

stem doesn't normally fill the curve with colour. Are you using a custom stem function per chance?

What does

which stem -all

returns?

[Joshua Scicluna]

It appears as filled because there is a substantial number of samples, when zooming in the stem lines appear… again with different colour. Refer to figure.

which stem -all

returns

C:\Program Files\MATLAB\R2018a\toolbox\matlab\specgraph\stem.m

[Guillaume]

"It appears as filled because there is a substantial number of samples, when zooming in the stem lines appear… again with different colour"

Ah, got you. I can't reproduce the behaviour in 2020a with 'opengl hardware' renderer and 1e6 points in the curve. How many points in your curves.

Unfortunately, I don't have 2018a installed anymore. You may want to look at Resolving low-level graphics issues. Switching renderer may resolve the problem.

Makes kind of pretty plots though...

[Joshua Scicluna]

Problem Solved!

I took a good look into the Resolving low-level graphics issues and tried to use the command

opengl('save','software')

which worked fine. The stem plot lines follow the colour of the markers.

Thanks for your help! @Guillaume