I am trying to use \watt in LyX, but I find that although it is a very simple case, I have spent 1 week to solve it but in vein.
First, I found out that if I want to use watt then I must use the siunits package, so I tried to add this in LyX 'Document-Setting-LaTeX Preamble' with \usepackage{siunits} but when I typed in \watt (according to siunits documentation) in LyX, it appears as \watt still, without changing into 'W' symbol, and when I see the pdf file, it is also 'watt'
Second, I find that, maybe my TexLive does not have the siunits package, so I tried to install this package in TexLive on Ubuntu 14.04, but I find that it is another complicated issue, as I didn't directly install TexLive in my system, instead, I install it by installing TeXMaker, during which, the Texlive was installed automatically, but I noticed that someone said that this installation might lose some useful packages....but I really have no idea how to check that if my Texlive had installed the package siunits.
It's a little complicated, but, anybody has some idea? Thank you!