%From: reingold@emr.cs.uiuc.edu (Edward M. Reingold)
%Newsgroups: comp.text.tex
%Subject: Re: short form references like [1-4]
%Date: 26 Mar 91 22:44:32 GMT
%Organization: University of Illinois at Urbana-Champaign
%
%In article <880@imec.UUCP> symons@imec.be (Jan Symons) writes:
%
%   with LaTeX, the \cite{key1,key2,key3,key4} puts a [1,2,3,4] reference
%   in the text. However, what I want to see is more like [1-4].
%
%   Can somebody please explain how this can be achieved with LaTeX ?
%
%
%Here is rangecite.sty that we cobbled together for just this purpose:
%
%-----------------------------rangecite.sty---------------------------------
% RANGECITE DOCUMENT-STYLE OPTION FOR ANY STYLE WITH NUMERIC CITATIONS
%
% This redefines the LaTex \@cite macro to gather consecutive citation numbers
% i,i+1,...,j into a range i-j
% 
% Nachum Dershowitz (nachum@cs.uiuc.edu)
% Edward M. Reingold (reingold@cs.uiuc.edu)
%
% These macros are in the public domain.  You may use them and copy them at
% will, provided you retain the authorship information.  We wrote these for
% temporary use in a single paper, so use them at your own risk!
%
% Written 12 Apr 1990
%
%
\newif\if@first%
\newcounter{@@@first}%
\newcounter{@@@state}%
%
%  A simple four-state finite automaton:
%        State 0:  No references in current range
%        State 1:  One reference in current range
%        State 2:  Two references in current range
%        State 3:  More than two references in current range
%
\newcounter{@@@next}%
\newcounter{@@@cur}%
\newcounter{@@@curt}%
\newcommand{\b@@@ENDLIST}{9999}%
\def\@citex[#1]#2{%
  \if@filesw\immediate\write\@auxout{\string\citation{#2}}\fi%
  \def\@citea{}%
  \@cite{%
     \@firsttrue%
     \setcounter{@@@state}{0}%
     \@for\@citeb:=#2,@@ENDLIST\do{%
         \@ifundefined{b@\@citeb}%
            {{\bf ?}%
             \@warning{Citation `\@citeb' on page \thepage \space undefined}}%
%        else%
            {\setcounter{@@@next}{\csname b@\@citeb\endcsname}%
             \ifcase\the@@@state%
%                  state 0:
               \setcounter{@@@state}{1}%
             \or%  state 1:
               \ifnum\value{@@@next}=\value{@@@curt}%
                  \setcounter{@@@state}{2}%
                  \setcounter{@@@first}{\value{@@@cur}}%
               \else%
                  \if@first{}\else{,\ }\fi%
                  \the@@@cur%
                  \@firstfalse%
               \fi%
             \or%  state 2:
               \ifnum\value{@@@next}=\value{@@@curt}%
                  \setcounter{@@@state}{3}%
               \else%
                  \setcounter{@@@state}{1}%
                  \if@first{}\else{,\ }\fi%
                  \the@@@first,\ \the@@@cur%
                  \@firstfalse%
               \fi%
             \or%  state 3:
               \ifnum\value{@@@next}=\value{@@@curt}%
               \else%
                  \setcounter{@@@state}{1}%
                  \if@first{}\else{,\ }\fi%
                  \the@@@first-\the@@@cur%
                  \@firstfalse%
               \fi%
            \fi%
         \setcounter{@@@cur}{\value{@@@next}}%
         \setcounter{@@@curt}{\value{@@@cur}}%
         \addtocounter{@@@curt}{1}}}}%
  {#1}}%