LaTeX header for Physicists

用LaTex作物理笔记时，有一些符号打起来很麻烦却反复出现。我们可以定义更简短的命令以增加输入速度。比如这篇博文LaTeX for Physicists就是这么做的。

我根据自己需要又作了一些增改，把它贴上来跟大家分享。嗯，感觉还得要个天文版的。

\usepackage{amsmath}
\usepackage{amssymb}
\usepackage{mathrsfs}

\newcommand{\abs}[1]{\left\lvert #1 \right\rvert}          % for absolute value
\newcommand{\avg}[1]{\left\langle #1 \right\rangle}        % for average
\newcommand{\norm}[1]{\left\lVert #1 \right\rVert}         % for norm

\let\f=\frac
\let\tf=\tfrac
\let\df=\dfrac
\let\rm=\mathrm
\let\bm=\boldsymbol

\let\overring=\r
\let\lslash=\l                         %l with a stroke
\renewcommand{\r}{\right}
\renewcommand{\l}{\left}

\let\vaccent=\v                        % rename builtin command \v{} to \vaccent{}
\renewcommand{\v}[1]{\boldsymbol{#1}}                 % for vectors
\newcommand{\uv}[1]{\hat{\boldsymbol{#1}}}            % for unit vector

\let\underdot=\d                       % rename builtin command \d{} to \underdot{}
\renewcommand{\d}[2]{\dfrac{\mathrm{d} #1}{\mathrm{d} #2}}       % for derivatives
\newcommand{\dd}[2]{\dfrac{\mathrm{d}^2 #1}{\mathrm{d} #2^2}}    % for double derivatives
\newcommand{\pd}[2]{\dfrac{\partial #1}{\partial #2}}            % for partial derivatives
\newcommand{\ppd}[2]{\dfrac{\partial^2 #1}{\partial #2^2}}       % for double partial derivatives
\newcommand{\mpd}[3]{\dfrac{\partial^2 #1}{\partial #2 \partial #3}}   % for mixed partial derivatives
\newcommand{\dif}{\mathrm{d}}        %upright d for diffrential

\newcommand{\me}{\mathrm{e}}        %constant e
\newcommand{\mi}{\mathrm{i}}        %constant i
%\DeclareMathOperator{\me}{e}          %which is better?

\let\divsymb=\div                             % rename builtin command \div to \divsymb
\renewcommand{\div}[1]{\nabla \cdot #1}             % for divergence
\newcommand{\grad}[1]{\nabla #1}                 % for gradient
\newcommand{\rot}[1]{\nabla \times #1}             % for curl

cf: http://www.dfcd.net/articles/latex/latex.html