MATLAB: Fplot add an undesired line

fplotlinewidthMATLAB

When I use fplot with LineWidth a dashed thick gray line appears on the right edge o the box. Example
h=fplot(@(u) u.*exp(u),[-6,1],'r-','LineWidth',3)
fplotbug.png
Without Linewidth the picture is OK

Best Answer

The gray line (that is always present (although it changes with the LineWidth parameter) indicates that the function increases or decreases without bound at that point.
There is no direct way to remove it, however you can get the XData and YData values from the fplot function and plot them separately: 
figure
h=fplot(@(u) u.*exp(u),[-6,1],'r-','LineWidth',3);
figure
plot(h.XData, h.YData, '-r', 'LineWidth',2)
The gray dashed line is now gone from the second plot.
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