In MATLAB R2016b, this can be accomplished using the ‘CapSize’ property of the Errorbar plot. The following code illustrates how to do this:
x = 0:pi/10:pi;
y = sin(x);
e = std(y)*ones(size(x));
figure
h = errorbar(x,y,e);
h.CapSize = 12;
In MATLAB versions R2014b through R2016a, this functionality is not present.
In MATLAB R2014a and earlier, you can change the width of these horizontal lines by modifying the ‘Xdata’ of each of them. The following code illustrates how to do this in an automated fashion:
hf = figure;
X = 0:pi/10:pi;
Y = sin(X);
E = std(Y)*ones(size(X));
ha = errorbar(X,Y,E);
hb = get(ha,'children');
Xdata = get(hb(2),'Xdata');
temp = 4:3:length(Xdata);
temp(3:3:end) = [];
% xleft and xright contain the indices of the left and right
% endpoints of the horizontal lines
xleft = temp; xright = temp+1;
% Increase line length by 0.2 units
Xdata(xleft) = Xdata(xleft) - .1;
Xdata(xright) = Xdata(xright) + .1;
set(hb(2),'Xdata',Xdata)
