# Underline at the same level

I want to underline alpha's and beta's, but at the same level. I mean, I don't want but . Maybe there is already a command that make it but I couldn't find it. The second image was obtained with the following command :

$\newlength{\espa} \settowidth{\espa}{$\alpha$}\rlap{\underline{\hspace{\espa}}}\alpha, \settowidth{\espa}{$\beta$}\rlap{\underline{\hspace{\espa}}}\beta$

which is hardly working but not totally. In normal math mode, no pbm. In scriptsize (or tiny or anything else) math mode, no pbm. But if I am in math mode within an exponent, then the \settowidth command does not seem to take into account that I am in sciptsize mode and, as a matter of fact, the underline is too long (e.g. ).

Any idea ?

• Would incorporating a \strut help to put all underlines at the same level? Mar 24 '11 at 11:12
• A \mathstrut would be more appropriate, assuming math mode is where you want to do it. It will scale with (sub)subscripts, which the regular \strut won't do. Mar 24 '11 at 12:08

$\underline{\smash{\beta}}$