\(
\newcommand{\pd}[2]{\frac{\partial #1}{\partial #2}}
\newcommand{\pdd}[2]{\frac{\partial^2 #1}{\partial {#2}^2}}
\newcommand{\fd}[2]{\frac{\mathrm d #1}{\mathrm d #2}}
\newcommand{\fdd}[2]{\frac{\mathrm d^2 #1}{\mathrm d {#2}^2}}
\newcommand{\lr}[1]{\left(#1\right)}
\newcommand{\lrm}[1]{\left[#1\right]}
\newcommand{\lrv}[1]{\left|#1\right|}
\newcommand{\ep}{\epsilon}
\newcommand{\dev}{\overrightarrow{\nabla}\cdot}
\newcommand{\devp}{\overrightarrow{\nabla}'\cdot}
\newcommand{\curl}{\overrightarrow{\nabla}\times}
\newcommand{\curlp}{\overrightarrow{\nabla}'\times}
\newcommand{\gra}{\overrightarrow{\nabla}}
\newcommand{\grap}{\overrightarrow{\nabla}'}
\newcommand{\inno}[2]{\int {#2}\;\mathrm d {#1}}
\newcommand{\ind}[3]{\int\limits_{#2} \mathrm d {#1}\;{#3}}
\newcommand{\indu}[4]{\int_{#2}^{#3} {#4}\;\mathrm d {#1}}
\newcommand{\inds}[3]{\oint\limits_{#2} \mathrm d {#1}\;{#3}}
\newcommand{\ket}[1]{\left|{#1}\right>}
\newcommand{\bra}[1]{\left<{#1}\right|}
\newcommand{\braket}[2]{\left<{#1}\mid{#2}\right>}
\newcommand{\re}{\text{Re}}
\newcommand{\im}{\text{Im}}
\newcommand{\lra}[1]{\overleftrightarrow{#1}}
\def\dbar{{\mathchar'26\mkern-12mu d}}
\)
Analytical Methods in Physics