Change size of math symbols

What is the matter with $\tilde{\scriptsize{\mathscr{O}}}$? Could anybody help me?

• Can you show a complete example? And also tell why you want this. – egreg Nov 23 '13 at 11:37
• I just have to use both $\mathscr{O}$ and a smaller $\mathscr{O}$. – ksj03 Nov 23 '13 at 12:19

Remarks

You need to use \scriptstyle rather than \scriptsize in math mode. Also keep in mind that \scriptstyle takes no arguments, but changes the style inside the current group. See also p. 292, Chapter 26 in the TeXbook.

Implementation

Compile with any plain TeX engine

$\tilde{\cal O}$
$\tilde{\scriptstyle {\cal O}}$
$\tilde{\scriptscriptstyle {\cal O}}$
\bye