How come I get different line thicknesses on different output devices using the same thickness value?
Line thicknesses displayed on different output devices (X11, PostScript, PDF, etc.) can be significantly different for the same line thickness value. This is due to several factors. Every device has a default, or nominal, line thickness (also sometimes call line width). This nominal line width is the width of a line drawn with the default thickness value of 1.0. In general this nominal line width is different for different devices. What a given device considers its default line width can vary from barely visible to fat. For example, the nominal line width for PostScript output may look thinner than a line drawn with the same width specification on an X11 window. Also, the results for X11 output can vary depending on the resolution of the output device. The linewidth scale factor is applied to the nominal line width on a given device. However, it will not necessarily produce lines that are exactly that factor bigger than the default width. In fact the scale factor may have no effect, or