let ab: Vec3 = (a, b).into();
println!("{}", make_vec!(ab));

Error: Could not start the command: pdflatex -synctex=1 -interaction=nonstopmode

\begin{align*}
\bf{A}^T_{\bf{-q-k}} S_{\bf{k}}^{\dagger} 
  \begin{pmatrix}
    \qty (1 + \cos(\bf{k \cdot a_3})) \hat{\sigma_2} + \sin(\bf{k \cdot a_3}) \hat{\sigma_1} & \hat{O} \\
    \hat{O} & - \qty (\cos(\bf{k \cdot a_1})+ \cos(\bf{k \cdot a_2})) \hat{\sigma_2} \\
    &- \qty (\sin(\bf{k \cdot a_1}) + \sin(\bf{k \cdot a_2})) \hat{\sigma_{1}}
  \end{pmatrix} 
S_{\bf{k}} \bf{A}_{\bf{k}} \bigg \}
\end{align*}