Say I want to reduce the space between two letters in math mode by 2/18 quad. Going all Die Hard 3, I put together 2 -3/18 quad \!
and add 4/18 quad with \:
. The problem is, though, that apparently the positive space gets squashed according to the current line's interword spacing while the negative space does not. So in extreme cases I get -6/18 quad which looks less than satisfying in my MWE and in the real world:
\documentclass[a5paper]{article}
\newcommand{\md}{\ensuremath{M\!\!\:D}}
\begin{document}
a a a a a a a a a a a a a a a a a a a a a a $\md$ a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a
aaaaaaaaaaaaaa aaaaaaaaaaaaaaaaaaaaa $\md$ aaaaaaaaaaaaaaaaaaa aaaaaaaaaaaaaa aaaaaaaaaa aaaaaaaaaaa aaaaaaaaaaaaa aaaaaaaaaaaaa aaaaaaaa
\end{document}
So why is inline math subjected to normal interword spacing adjustments and how can I switch it off? (I can imagine this leading to problematic results in many formulae, even when not doing such strange spacing arithmetic as I did.)
\quad
or ` \!` or others are rubber spaces. Try to use\mbox{\ensuremath{M\!\!\:D}}
.\!
does not actually appear to be a rubber space, only\:
is.