preamble.tex

\documentclass[a4paper,12pt]{article}
\usepackage[finnish]{babel}
\usepackage[utf8]{inputenc}
\usepackage{amsmath}
\usepackage{graphicx}
\usepackage{caption}
\usepackage{subcaption}
\usepackage{epstopdf}
\usepackage{gensymb}
\usepackage{subcaption}
\usepackage{color}			
\usepackage{listings}
\usepackage{setspace}
\usepackage{amssymb}
\usepackage{epstopdf}
\usepackage{enumitem}
\usepackage[parfill]{parskip}

%partial derivative
\newcommand{\pd}[2]{\frac{\partial #1}{\partial #2}}
%bra-ket notation
\newcommand{\bra}[1]{\left\langle #1 \right|}
\newcommand{\ket}[1]{\left| #1 \right\rangle}
\newcommand{\braket}[2]{\left\langle #1 \big| #2 \right\rangle}

%upright subscripts
\begingroup\lccode`~=`!
\lowercase{\endgroup\def~}#1{_{\mathrm{#1}}}
\mathchardef\exclam=\mathcode`!
\AtBeginDocument{\mathcode`!=\string"8000 }

%uprigth mu (or any greek letter)
\usepackage{xspace}
\def\mum{\ensuremath{\upmu \mathrm{m} \xspace}}
%\usepackage[]{mcode}
%\lstset{
%	literate = {ö}{{\"o}}1
%			{ä}{{\"a}}1
%			{€}{{\euro}}1
%} 

\begin{document}
\begin{equation}
\braket{\psi!1}{\psi!2} = \pd{x}{t}
\end{equation}
\end{document}