Marker shape (take 'o') not as expected at large (50) linewidths and markersize (50)?

Running this:

x=0:2:10;
y=x.^2;
p=plot(x,y,'LineWidth',50,'Marker','o','MarkerSize',50,...
'MarkerEdgeColor','b','MarkerFaceColor',[0.5,0.5,0.5]);

leads to:

Markers can be seen to be rather '+' than 'o'. I have similar problems with most other markers. Any help to resolve this is appreciated.

Thanks!

[KSSV]

It looks fine in my version of MATLAB. I am using 2015a...

Answer 1

[Walter Roberson]

In R2014a on OS-X, I do not see the marker as a plus, but I do see it as a distorted circle. With additional testing, I see that the LineWidth is being applied to creating the Marker as well.

Work-Around: plot() once without markers but with the LineWidth desired for the line. plot() a second time with the desired marker and with no LineWidth and with LineStyle 'none', to draw the markers properly.

[Bram Veenhuizen]

Thanks, Walter, for your answer. Unfortunately, it does not yet lead to a solution I can use. I want the marker to have thick borders, just as the line. I think filled patches may work (not for circular markers, where rectangles(!) could be used), but this requires some more programming work.

I find it a bit disconcerting that one of the most universally used matlab functions (plot) can so easily be "misled" and needs work-arounds to produce "proper" results. (BTW, I get the similar looking results in 2015b and 2016a). Thanks again, but I'm still open for solutions for my case. Maybe someone feels challenged to come up with "patch/rectangle" based work-around or has a better idea?

[Walter Roberson]

MarkerSize 50 means 50 square points, so for a square that would be about 7 points x 7 points. LineWidth 50 means 50 points wide, so 25 points from the center to the edge. Draw two lines with their centers about 7 points part and each line 50 points wide. The result is not going to look anything like you had hoped.

So you can have thick borders, but they will need to be a lot thinner than the line width, probably notably less than 1/2 of sqrt() of the marker size. Each individual straight line of the marker (including curves approximated as straight lines) is drawn as an individual brush stroke with straight edges. That produces spikes -- the strokes are not chamfered.

scatter() has a 'fill' option, by the way, if your aim is to fill the markers. Or Use a marker edge color the same as the marker face color as requesting a marker face coloring means you want filling.

[Bram Veenhuizen]

Thanks for your reply, Walter. I will do this plotting job in excel which produces proper thick-edged markers as well as chamfering out of the box.