nomencl package : sort by order of appearance

Question

In the nomencl package, how can I make the symbols print by order of appearance in the LaTeX code?

Answer 1

As far as I know, nomencl does not support this out of the bag. Here's a hacky way to do it instead.

Basically it is a redefinition of the \nomenclature[]{}{} command, to ignore the sorting argument (i.e. the optional argument in \nomenclature) and to use a counter-based sorting method instead. Whenever \nomenclature is called, the counter @nomcount raises by one. We then take advantage of makeindex's sorting algorithm which treats numbers as per normal (8<34<111), and so the entries will be printed in order of use.

I have included a toggle for you to switch this sorting behaviour 'on' and 'off'. With

\settoggle{nomsort}{<bool>}

If <bool> is set to true, then we activate sort by use (which is your desired effect). If <bool> is set to false then we return to normal usage of nomencl (using the optional argument of \nomenclature and what not).

\documentclass[]{article}
\usepackage{etoolbox}
\usepackage[]{nomencl}   
    \makenomenclature

\providetoggle{nomsort}
\settoggle{nomsort}{true} % true = sort by use, false = sort as usual

\makeatletter
\iftoggle{nomsort}{%
    \let\old@@@nomenclature=\@@@nomenclature        
        \newcounter{@nomcount} \setcounter{@nomcount}{0}%
        \renewcommand\the@nomcount{\two@digits{\value{@nomcount}}}% Ensure 10>01
        \def\@@@nomenclature[#1]#2#3{% Taken from package documentation
          \addtocounter{@nomcount}{1}%
        \def\@tempa{#2}\def\@tempb{#3}%
          \protected@write\@nomenclaturefile{}%
          {\string\nomenclatureentry{\the@nomcount\nom@verb\@tempa @[{\nom@verb\@tempa}]%
          \begingroup\nom@verb\@tempb\protect\nomeqref{\theequation}%
          |nompageref}{\thepage}}%
          \endgroup
          \@esphack}%
      }{}
\makeatother


\begin{document}
    \nomenclature{$j$}{Appears first} 
    \nomenclature{$i$}{Appears second}
    \nomenclature{$h$}{Appears third}
    \nomenclature{$g$}{Appears fourth}
    \nomenclature{$f$}{Appears fifth}
    \nomenclature{$e$}{Appears sixth}
    \nomenclature{$d$}{Appears seventh}
    \nomenclature{$c$}{Appears eighth}
    \nomenclature{$b$}{Appears ninth}
    \nomenclature{$a$}{Appears tenth~(last)}
    \printnomenclature

    Note that $d$ appears first because it is declared first.

    Note also the 10th entry is sorted after the 9th.
\end{document}

To be honest, though, it's probably easier and more consistent to do it with the glossaries package, as @NicolaTalbot mentioned in the comments.

Answer 2

Let us say that you want to print variables z,y and x using nomencl with

z coming first followed by y and x. You key in the code as below: 

\nomenclature{$z$}{This is the first variable}

\nomenclature{$y$}{This is the second variable}

\nomenclature{$x$}{This is the third variable}

\printnomenclature

The nomenclature package sorts the variables in alphabetical order. The default output for an input code given above will be:

which may not be the desired one. To generate the nomenclature list in the input order (in the order as they appear) can be accomplished by the including the order number within the optional square brackets. The modified code with a longer list of variables is illustrated below:

\nomenclature[[1]]{$z$}{This is the first variable}

\nomenclature[[2]]{$y$}{This is the second variable}

\nomenclature[3]{$x$}{This is the third variable}

\nomenclature[4]{$w$}{This is the fourth variable}

\nomenclature[5]{$v$}{This is the fifth variable}

\nomenclature[6]{$u$}{This is the sixth variable}

\nomenclature[7]{$t$}{This is the seventh variable}

\nomenclature[8]{$s$}{This is the eighth variable}

\nomenclature[9]{$r$}{This is the ninth variable}

\nomenclature[a1]{$q$}{This is the tenth variable}

\nomenclature[a2]{$p$}{This is the eleventh variable}

\printnomenclature

The desired output appears below:

Note the numbering scheme used within the square brackets to extend beyond 10 variables. Hope this helps. Thank you.