In Document>Settings>Math Options, checking the 'Use AMS math package
automatically' option doesn't mean exactly that. I use LyX for
constructing diagrams with PSTricks and enter the code in ERT (LyX's
PostScript View and Update buttons are excellent for this). I wanted to
label an angle with pi/4 and entered
$\tfrac{\pi}{4}$
but got an undefined control sequence message for my troubles, despite
the AMS math package option being checked. When I added
\usepackage{AMSmath}
manually in the document preamble, all was well.
When I enter the same expression in LyX's math editor, the AMS math
package does load automatically. The code in both cases looks identical
in the View Source window.
A bug? Confusing at least.
(LyX 1.6.8; ponderous Windows Vista)
Andrew Parsloe
