# Double Subscript in Math Mode

\usepackage{amsmath}
\usepackage{siunitx}
$$2I_{x}S_{z} \overset{\ang{90} \text{Pulse_{I_y}}}}{\rightarrow}$$


For some reason this is not working. For the overset text, I want a double subscript. Thank you.

• You have to close the \text{Pulse} because if not the superscript is set in text mode. By the way, I would use \operatorname{Pulse} or define \DeclareMathOperator\Pulse{Pulse} and use \Pulse. – Manuel Jun 28 '16 at 16:12
• there is also another "extra" close brace following the subscript, after follwing @Manuel's suggestions. and i'm surprised you didn't get a ! Missing \$ inserted. error. – barbara beeton Jun 28 '16 at 16:15
• @barbarabeeton I got many errors. – HighEnergy Jun 28 '16 at 16:22
• when you get errors, it's important to fix them, starting with the first one reported. subsequent errors are often just side effects from an earlier one, and will disappear when the initial problem is fixed. – barbara beeton Jun 28 '16 at 19:10
• I would like to point out that \xrightarrow and overset differ in that overset simply "prints" the text above the underset symbol while xrightarrow lengthens the underset symbol for better visual effect – HighEnergy Jul 7 '16 at 15:52

You can't use _ in the argument to \text. You should better use \mathrm and \xrightarrow:

\documentclass{article}
\usepackage{amsmath}
\usepackage{siunitx}

\begin{document}

$$2I_{x}S_{z} \xrightarrow{\ang{90}\ \mathrm{Pulse}_{I_y}}$$

\end{document}


• Might \text{Pulse}_{I_y} be better semantically? – Taiki Jun 28 '16 at 16:53
• @Taiki No, it would come out italic if the equation is inside a theorem statement. – egreg Jun 28 '16 at 16:56
• Ah interesting... How about \textnormal{Pulse}_{I_y}? – Taiki Jun 28 '16 at 17:09
• @Taiki Might be an alternative, but for a single word without special characters, the \mathrm solution is more efficient. – egreg Jun 28 '16 at 17:12