Lifting a math symbol in LaTeX

Question

I'm using the symbol \otimes as a unary operator and it's vertical alignment doesn't seem right to me. It wants to sit a bit below the baseline. For example, if I define \newcommand{\myop}{\ensuremath \otimes}, then $\myop I$ becomes

and $F_{\myop I}$ becomes

I tried using \raisebox to fix this, e.g.,

\newcommand{\myop}{\ensuremath \raisebox{1pt}{$\otimes$}}

This fixes $\myop I$:

But \raisebox doesn't seem to be sensitive to subscripts. The operator stays the same size while everything around it shrinks:

The problem, I think, is that \raisebox creates its own LR box, which doesn't inherit the settings in the surrounding math environment. Is there a version of \raisebox that "respects math"?

Answer 1

$F_{\raisebox{1pt}{\scriptsize$\otimes$} I}$

Answer 2

That is indeed the correct vertical placement for the operator, although it seems slightly too low next to uppercase letters. Try using it with lowercase letters to see that. If it were higher, this would look odd.

Answer 3

Try \mathchoice (or \mathpalette):

\newcommand{\myop}{%
  \mathchoice{\raisebox{1pt}{$\displaystyle\otimes$}}
             {\raisebox{1pt}{$\otimes$}}
             {\raisebox{0.5pt}{$\scriptstyle\otimes$}}
             {\raisebox{0.2pt}{$\scriptscriptstyle\otimes$}}}

The amsopn documentation says:

... the vertical spacing may not be optimal in script and scriptscript sizes. Unfortunately TeX provides no easy way to do math mode vertical spacing that varies with current math style like mu units.