latexnew.sty

% deps
\usepackage{mathtools}

%spacing
\titlespacing*{\subsubsection} {0pt}{0.5ex}{2.0ex}
\titlespacing*{\subsection} {0pt}{0.5ex}{2.0ex}

%% math commands
% number spaces
\newcommand{\R}{\ensuremath\mathbb{R}}
\newcommand{\Q}{\ensuremath\mathbb{Q}}
\newcommand{\N}{\ensuremath\mathbb{N}}
\newcommand{\Z}{\ensuremath\mathbb{Z}}
% matrix and vectors
\renewcommand{\v}[1]{\textbf{#1}}
\newcommand{\ma}[1]{\textbf{#1}}
% fractions
\newcommand{\fr}{\dfrac}
%differentation
\newcommand{\dd}[1]{\frac{d}{d#1}}
\newcommand{\dt}[1]{\frac{d#1}{dt}}
\newcommand{\pd}[1]{\frac{\partial}{\partial #1}}
\newcommand{\grad}{\nabla}
% limits and sums
\let\limi\lim
\let\liminfi\liminf
\let\limsupi\limsup
\let\sumi\sum
\renewcommand{\lim}{\limi\limits}
\renewcommand{\sum}{\sumi\limits}
% abs and norm (https://tex.stackexchange.com/questions/43008/absolute-value-symbols)

\DeclarePairedDelimiter\abs{\lvert}{\rvert}%
\DeclarePairedDelimiter\norm{\lVert}{\rVert}%

% Swap the definition of \abs* and \norm*, so that \abs
% and \norm resizes the size of the brackets, and the 
% starred version does not.
\makeatletter
\let\oldabs\abs
\def\abs{\@ifstar{\oldabs}{\oldabs*}}
%
\let\oldnorm\norm
\def\norm{\@ifstar{\oldnorm}{\oldnorm*}}
\makeatother