
\let\oldint\int 		\def\int#1\dd{\oldint#1\;\dd}
\let\oldiint\iint		\def\iint#1\dd#2\dd{\oldiint#1\;\dd#2\;\dd}
\let\oldiiint\iiint	\def\iiint#1\dd#2\dd#3\dd{\oldiiint#1\;\dd#2\;\dd#3\;\dd}
\newcommand{\infint}[2] 		{\int_{-\infty}^\infty#2\dd#1}
\newcommand{\partiald}[2]		{\frac{\partial#1}{\partial#2}}
\newcommand{\hpdbyd}[2][]	{\partial{#1}/\partial{#2}}
\newcommand{\pd}[2]			{\dfrac{\partial#1}{\partial#2}}
\newcommand{\dd}				{\mathrm{d}}
\newcommand{\hdbyd}[2][]	{\dd{#1}/\dd{#2}}
\newcommand{\dbyd}[2][]		{\frac{\dd#1}{\dd#2}}
\newcommand{\dbydt}[1]		{\frac{\dd#1}{\dd t}}
\newcommand{\hpd}[2]		{{\partial#1}/{\partial#2}}
\newcommand{\grad}			{\boldsymbol{\nabla}}
\newcommand{\hfrac}[2] {#1/#2}
\newcommand{\hpfrac}[2] {(#1/#2)}

\newcommand*{\reals} 		{\mathbb{R}}
\newcommand{\define}		{\overset{\text{\tiny def}}{=}}
