Write a derivative operator without denominator using diffcoef

Question

I recently discovered the diffcoef package and the power of xtemplate. The first one encompasses almost everything I was doing with personal macros for derivative operators.

However, I was wondering if it is possible to simply tune the command \diffp to obtain a compact version of the derivative operator, where the denominator is subscripted instead.

Here is a MWE, where the right hand side of the equation should look like the left hand side:

\documentclass{article}

\usepackage{diffcoeff}

\begin{document}

    \diffdef{p}{ % Something that should remove the fraction style
        op-symbol = \partial,
        op-symbol-alt = none
        }
    \begin{equation}
        \partial_x f= \diffp*{f}{x} % now the LHS and RHS are different...
    \end{equation}
\end{document}

Of course the purpose is not to do something like \newcommand{\diff2}[2]{\dlp_{#1}#2} because I would like to retain the flexibility of the diffcoef package. For example, I also wish to be able to write with the same command:

\partial_{\frac{1}{b}}^{z}\partial_{xy}^{z-1}a=\diffp[z,z-1]{a}{\frac{1}{b},xy}

So is it possible to remove the fraction style of the \diffp command with diffcoef? If not, is it possible to implement a new command, which maintains the syntax and flexibility of \diffp (perhaps via xtemplate)?

Answer 1

The derivative might have the functionality you seek with it's \pdif command. The package uses a key-value interface for setting options. This can be done on a individual basis that only apply to a single differential/derivative e.g. \pdif[key-value]{x,y,z}. One can also set the options for all differentials /derivatives with \derivset{\MacroName}[key-value], with \MacroName being \pdif, \pdv or other derivatives/differentials defined by the packages or you.

\documentclass{article}
\usepackage{amsmath}
\usepackage{derivative}
\begin{document}
    \begin{align}
        \pdif[order={z,z-1}]{\frac{1}{b},xy}  a \\
        \pdif*[order={z,z-1}]{\frac{1}{b},xy} a \\
        \pdif[style-notation=single, order={z,z-1}]{\frac{1}{b},xy} a \\
        \pdif[style-notation=multiple, order={z,z-1}]{\frac{1}{b},xy} a \\
        \pdif[style-notation=mixed, order={z,z-1}]{\frac{1}{b},xy} a \\
    \end{align}
\end{document}

Alternatively, if one wants other macros names for them, I suggest defining new ones with the commands in section 5 of the documentation.

Answer 2

I believe the package defines \dl.p. and \dlp to write partial differential. From what I understand from the documentation, when you use \diffdef{variant}{key-value} you define both \diff.variant. and \dl.variant.. Then it is just a matter of defining \NewDocumentCommand\SomeOtherName{}{ \diff.variant. } if you don't want to use dots.

\documentclass{article}
\usepackage{amsmath}
\usepackage{diffcoeff}
\begin{document}
    \begin{align}
        \dl.p.{x} \dlp{x} \\
        \dl.p._{x} \dlp_{x}
    \end{align}
\end{document}

Alternatively, there are other packages with these features as well.