% This is apeqnum.sty
% 8-November-1990
% Don Hosek
% Style option for article.sty and derivatives; causes equations
% to be numbered A1, A2, A3, B1, etc. in a document.

% First save a copy of the old meaning of \appendix
\let\apeqnum@appendix=\appendix 

% Now, we will redefine \appendix so that it does the following:
%   (1) The old functions of \appendix (\apeqnum@appendix)
%   (2) Causes equations to be numbered beginning from one at
%       the beginning of each appendix (this is accomplished
%       for the article style with the command
%       \@addtoreset{equation}{section})
%   (3) Change the definition of \theequation (which prints the
%       equation numbers) so that the appendix letter is prepended.
\def\appendix{%
   \apeqnum@appendix % (1)
   \@addtoreset{equation}{section} % (2)
   \def\theequation{\thesection\arabic{equation}}} % (3)