[Tex/LaTex] Overfull hbox on a tiny equation


My microscopic equation is 2.8 points too wide for some reason, which is quite a lot. I am reluctant to ignore the warning because if I get more of them I'll start missing important things.

Code is:

Applying Snell's law (Equation \eqref{eq:snell}) twice gives us:
    \theta_2 &= arcsin \left( \frac{n_{vacuum}}{n_{mylar}} sin(\theta_1) \right) \\
    \theta_1 &= arcsin \left( \frac{n_{mylar}}{n_{vacuum}} sin(\theta_0) \right)
which simplifies to
    \theta_2 = \theta_0
We saw earlier that there was a critical angle [blah blah more text...]

And the warning is:

Overfull \hbox (2.80157pt too wide) (page 6)

on line 226, which is the line containing the tiny \theta_2 = \theta_0.

I'm probably missing something relatively obvious but I just can't see it. Any idea ?

Best Answer

Local modification of the mu-lengths/skips (math-unit skips) could condense the equation enough to avoid the warning yet still produce a consistent enough look to your equation compared to others. Herbert Voß' mathmode document illustrates the different locations where mu-skips are used in an equation:

Muskips in math mode

The default setting for these mu-skips are

\medmuskip=4mu plus 2mu minus 4mu
\thickmuskip=5mu plus 5mu

where 1mu=0.05556em. Perhaps merely adding some shrinkability to \thinmuskip=3mu minus 3mu would help.

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