function r=plus(a,b)%PLUS Addition for Rational Polynomial Objects. (MM)% D.C. Hanselman, University of Maine, Orono ME 04469% 3/27/98% Mastering MATLAB 6, Prentice Hall, ISBN 0-13-019468-9if isnumeric(a)	rn=mmpadd(a*b.d,b.n);	rd=b.d;	rv=b.v;elseif isnumeric(b)	rn=mmpadd(b*a.d,a.n);	rd=a.d;	rv=a.v;else % both polynomial objects	if ~isequal(a.d,b.d)		rn=mmpadd(conv(a.n,b.d),conv(b.n,a.d));		rd=conv(a.d,b.d);	else		rn=mmpadd(a.n,b.n);		rd=b.d;	end	if ~strcmp(a.v,b.v)		warning('Variables Not Identical')	end	rv=a.v;endr=mmrp(rn,rd,rv);