MATLAB: Does LineWidth not change when I set the LineWidth property of the plot

linewidthMATLABresolutionscreenscreenpixelsperinch

Why is there no difference in the linewidth shown below?
subplot(2,1,1)
h1 = plot(1:10);
set(h1,'LineWidth',1.1)
subplot(2,1,2)
h2 = plot(1:10);
set(h1,'LineWidth',1.4)

Best Answer

This issue has to do with the fundamental resolution of your screen. Based on the description of the linewidth property:
 <http://www.mathworks.com/access/helpdesk/help/techdoc/ref/line_props.html>
Which says that 1 point = 1/72 inches. We also know that the ScreenPixelsPerInch which is a fundamental property of your screen can be found by performing a GET operation as follows:
get(0,'ScreenPixelsPerInch')
With this information you can obtain Pixels/Point [Dividing Pix/Inch by Points/Inch].
So for the change in Line Width to occur the number of Pixels/Point would need to be a whole pixel before change is noticed.
Illustrative Example:
close all
subplot(2,1,1)
h1 = plot(1:10);
set(h1,'LineWidth',1.1)
subplot(2,1,2)
h2 = plot(1:10);
Line_Width = 1.0;
for i = 1:100
      clc
      Pixels_Per_Point = (get(0,'ScreenPixelsPerInch')/72);
      subplot(2,1,2)
      set(h2,'LineWidth',Line_Width)
      Pixel_Width_Pts = Pixels_Per_Point*Line_Width
      Line_Width   = Line_Width + 0.1
      pause
end
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