# How to put an inequality sign along with a letter as a subscript when using equations?

First time posting, sorry if my question in the title isn't clear enough. To clarify, I'm trying to put an inequality sign, more specifically the sign > alongside a given Greek letter (alpha) after a given line assumption.

I want to put have something like this, which was done in Word as a draft.

Whereas in LaTeX, the outcome is like this

A sample of my work is as follows

FOC$$\frac{\partial G}{\partial q} = \mu_z - r_0 - 2\alpha q\sigma_z^2 \label{eq:1.6}$$\\
SOC$$\frac{\partial^2G}{\partial q^2} | _\alpha >0 = -2\alpha\sigma_z^2 < 0 \label{eq:1.7}$$
From \ref{eq:1.3} solving for q yields
\begin{align*}
\mu_z - r_0 = 2\alpha q\sigma_z^2
\end{align*}
$$q = \frac{u_z - r_0}{2\alpha\sigma_z^2}$$


Notice that the inequality doesn't go underneath with the letter, trying to overcome this but still haven't found a solution.

• If a subscript (or superscript) has more than one character, you need to enclose it in braces (e.g. |_{\alpha>0}). Otherwise LaTeX has no way to know where the subscript ends. – Ian Thompson Jan 10 '17 at 22:04
• – Au101 Jan 10 '17 at 22:19

Put {} around the underscript.

FOC
$$\frac{\partial G}{\partial q} = \mu_z - r_0 - 2\alpha q\sigma_z^2 \label{eq:1.6}$$
SOC
$$\frac{\partial^2G}{\partial q^2} | _{\alpha >0} = -2\alpha\sigma_z^2 < 0\label{eq:1.7}$$
From \eqref{eq:1.7} solving for $q$ yields
\begin{align}
\mu_z - r_0 &= 2\alpha q\sigma_z^2\notag\\
q &= \frac{u_z - r_0}{2\alpha\sigma_z^2}
\end{align}


• ... off-topic: \left.\frac{\partial^2G}{\partial q^2}\right|_{\alpha >0} = -2\alpha\sigma_z^2 < 0 \label{eq:1.7} will give more nice result. By the way, your answer should have form of complete small document ... – Zarko Jan 10 '17 at 22:18
• @Zarko I'd much prefer something like \Big|_{\alpha>0} or \bigg|_{\alpha>0} rather than \left. and \right|. – egreg Jan 10 '17 at 22:40
• for this reason I titled my comment "off-topic" ... :). you solve issue of subscripts! – Zarko Jan 11 '17 at 0:15