In a recent attempt to make a general partial derivative macro i came across the xparse package.
The problem is that the default latex macro command \newcommand
only allows for one optional argument and I wanted to make a command that could take 3 argument. The variable, the function, and the order of derivative. I turns out that this is not so easy as it might sound. At lest not without using xparse
. With xparse
it is quit easy.
\usepackage{xparse} %needed for DeclareDocumentCommand
\DeclareDocumentCommand{\pder}{ O{} O{} m }{\frac{\partial^{#2}#1}{\partial#3^{#2}}}
First we call the xparse
package as usual with \usepackage{}
. Then we use \DeclareDocumentCommand
which takes on 3 values. First we have to give your macro a new name. I choose \pder
for partial derivative.^{1} The second command defines optional and mandatory arguments. I choose the first 2 variables to be optional by o{}
. You can put a default value in {}
if you desire. The last file is simply the latex formula with #1
for the first variable, #2
for the second and so on.
If we then call
\pder{x}
\pder[f]{x}
\pder[f][2]{x}
the result is

Donâ€™t use
\pd
. It does not work. ↩