So, I have been using org-mode for taking my research notes for some time now. I love how I can seamlessly export to both latex (for my papers) and html (for my blog). However, whenever I define macros with \newcommand with #+LATEX_HEADER, these do not show up in the HTML export at all.
I currently handle this by putting the all these commands as (\newcommand \newcommand etc. etc.) at the top and then manually removing the "(" and ")" from the tex file.
What I wish I could do was to keep a drawer for these commands and customize html and latex export of org mode to handle this drawer appropriately.
For example, I would add the following in the org file:
:LATEX_MACROS:
\newcommand{\norm}[1]{\lVert{#1}\rVert}
\newcommand{\abs}[1]{\lvert{#1}\rvert}
\newcommand{\half}{\frac{1}{2}}
:END:
And after export, this shows up in the latex file verbatim in header section and in the html file as
\(
\newcommand{\norm}[1]{\lVert{#1}\rVert}
\newcommand{\abs}[1]{\lvert{#1}\rvert}
\newcommand{\half}{\frac{1}{2}}
\)