# No way to plot correctly dashed and dotted lines using painters

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Rodrigo on 27 Jan 2023
Edited: Rodrigo on 23 Feb 2023 at 18:10
I know this is an old issue, and believe me, I've been trying all found "solutions" all the week long. None has really worked. Here's an examplary code of 4 responses for underdamped systems used in Matlab 2019a:
K = 2;
w01 = 1;
w02 = 2;
Zeta1 = 0.3;
Zeta2 = 0.7;
t = 0:0.1:15;
s = tf('s');
P1 = K*w01^2/(s^2 +2*Zeta1*w01*s +w01^2);
P2 = K*w01^2/(s^2 +2*Zeta2*w01*s +w01^2);
P3 = K*w02^2/(s^2 +2*Zeta1*w02*s +w02^2);
P4 = K*w02^2/(s^2 +2*Zeta2*w02*s +w02^2);
f = figure;
f.Position = [100 100 700 375];
p = stepplot(P1,'k-',P2,'k--',P3,'k:',P4,'k-.',t)
p = resppack.timeplot
grid
set(findall(gcf,'type','line'),'linewidth',1);
set(gcf, 'Renderer', 'painters');
p.AxesGrid.XUnits = '';
legend('$\zeta = 0,3$ ; $\omega_0 = 1$','$\zeta = 0,7$ ; $\omega_0 = 1$','$\zeta = 0,3$ ; $\omega_0 = 2$','$\zeta = 0,7$ ; $\omega_0 = 2$','interpreter','latex')
xlabel('Time (s)')
ylabel('Amplitude')
title('')
Guess what? I want it for a publication, i.e., it must be vectorial.
I tried all possible solutions inside Matlab figure (save as, export, changed parameters...). Also tried export_fig and matlabfrag -- which are very good tools, I admit. They just didn't solve the issue.
export_fig seems to have more options, so I'll detail a bit more what happens with it. Using the code above all the lines seems solid after some time. If I change from 'painters' to 'openGL', then the lines appear the way it should be. However, in this case there's no sense to use export_fig using 'painters' again (and obviously, it doesn't work either). Saving as .png with 'screen' resolution is not an option.
Tired of trying with vectorials, I gave up and decided to use .png with higher resolution (600 dpi) both inside the figure environment and also using export_fig. Yes, it seems to work, but the spaces and lengths of dashes changed too! And the lines in the legend look horrible, mainly the dotted.
I just wanted a vectorial figure in the way it pops up to me when it opens. Am I asking too much?
Adam Danz on 30 Jan 2023
I ran the code in your question to produce the plot. This helps us see the problem you mentioned in the comment above regarding dashed lines. I was able to reproduce the bug in MATLAB Online and reported the issue. I'll add an answer shortly to share a workaround.

Adam Danz on 30 Jan 2023
Edited: Adam Danz on 23 Feb 2023 at 12:57
Thanks for reporting this issue. Here's a workaround I came up with after some trial and error.
After running the code from your question, move the curves to a new figure, set the decorations and the renderer, then export. I tested this in R2019a and MATLAB Online. The resultant pdf is attached and a screenshot of the vectorized pdf is below (the screenshot, of course, is not vectorized). Check that your legend strings are in the correct order after copying!
h = findall(f,'type','line');
iscurve = strcmpi({h.Tag},'Curves');
newfig = figure;
newax = axes(newfig);
hold on
newh = copyobj(h(iscurve),newax);
box on
grid on
legend('$\zeta = 0,3$ ; $\omega_0 = 1$','$\zeta = 0,7$ ; $\omega_0 = 1$','$\zeta = 0,3$ ; $\omega_0 = 2$','$\zeta = 0,7$ ; $\omega_0 = 2$','interpreter','latex')
xlabel('Time (s)')
ylabel('Amplitude')
set(newfig, 'Renderer', 'painters') % not needed in recent releases; after legend
% Export
print('test.pdf','-dpdf')
Update: easier workaround
Alternatively, you can merely remove the z-data from all lines to solve this problem. Thanks again for reporting it.
% f is the original figure handle to the stepplot
h = findall(f,'type','line');
set(h, 'ZData', [])
Rodrigo on 30 Jan 2023
Edited: Rodrigo on 23 Feb 2023 at 18:10
Incredible, worked like a charm! I can't understand why you need another figure for that, but in the end it doesn't matter. I must congratulate you, Adam! You really solved an old issue that very few people did.
Update:
And it's now even better with Adam's update. Thanks again!

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