Define $\LaTeX$ Commands

1. Define new Commands:
   

   LaTeX Listing: /usr/local/Slides/PreAmbles/NewCommands.tex. PDF   ZIP*   \newcommand{\Vector}[1]{\underline{\mathbf{#1}}} \newcommand{\Matrix}[1]{\underline{\underline{{\mathbf{#1}}}}} \newcommand{\Result}[1]{\underline{\underline{~~#1~~}}}

2. \renewcommand{command}
{
   %put latex statements here
}
   
3. Conditionals
   
   \pgfmathparse{2*(1-cos(\t))} \let\ft\pgfmathresult;
\ifthenelse{\lengthtest{ \ft pt > 0 pt}}
{
        \pgfmathparse{1/sqrt(\ft)} \let\ft\pgfmathresult;
        \coordinate (t) at ($\ft*(i)+\ft*(p)$);
}{}


\IfFileExists
{
      Existent
}{
      Nonexistent
}