function af=afform(m,ph,pv,overlap)
% AFFORM builds the subdomain matrix.
%
% function af=afform(m,ph,pv,overlap)
%
h=1/(m+1);
[lv,rv]=partition(m,pv,overlap);
if pv~=ph
	disp('error in afform.m');
	return
end
mx=rv(1)-lv(1)+1;
af=pmat2(mx,mx,h);