calibcant/theory.tex: Add S_{xx} and r_{xx} to the nomenclature

Thanks Mom!

diff --git a/src/calibcant/theory.tex b/src/calibcant/theory.tex
index ea0977a6a0b94162c51468aedaa1fba1f08b36b5..86ac487da1c59b110e544aa971b805c97fc6b1d4 100644 (file)
--- a/src/calibcant/theory.tex
+++ b/src/calibcant/theory.tex
@@ -98,8 +98,14 @@ where $r_{xx}(t)$ is defined in terms of the expectation value
 \begin{align}
   r_{xx}(t) &\equiv \avg{x(\tau)\conj{x}(\tau-t)} \;,
        &\text{\citep{wikipedia-wiener-khinchin}}
+    \label{eq:autocorrelation}
 \end{align}
 and $\conj{x}$ represents the complex conjugate of $x$.
+%
+\nomenclature{$S_{xx}(\omega)$}{Two sided power spectral density in
+  angular frequency space (\cref{eq:wiener_khinchin}).}
+\nomenclature{$r_{xx}(t)$}{Autocorrelation function
+  (\cref{eq:autocorrelation}).}
 \nomenclature{$\conj{z}$}{Complex conjugate of $z$}
 
 \subsection{Highly damped case}