How can I put a unary minus sign after a column separator?

Question

I am using the aligned environment in order to have a sequence of left-aligned equations.

In this latex code:

\[
\begin{aligned}
& a = b \\
& -c = d
\end{aligned}
\]

There is some space between the minus sign and the "c" even though I want it to be a unary minus.

How can I make this minus sign that comes after an & be a unary minus?

Ideally I would like to have a way to do this that works with KaTeX, since that is what I'm using to render math (although this issue appears to happen with pdflatex too.)

Answer 1

Simply encase the - symbol in curly braces. Doing so changes the symbol's math status from bin to ord (ordinary).

\[
\begin{aligned}
& a = b \\
& {-}c = d
\end{aligned}
\]

---

A full MWE:

\documentclass{article}
\usepackage{amsmath}
\begin{document}
\[
\begin{aligned}
& a = b \\
& -c = d\\
& {-}c = d
\end{aligned}
\]
\end{document}