# $Source: /u/maple/research/lib/DEtools/src/RCS/eigenring,v $
# $Notify: hoeij@sci.kun.nl $

macro(
	DF=`DEtools/diffop/DF`,
	x=`DEtools/diffop/x`,
	eigenring=`DEtools/diffop/eigenring`,
	endomorphism_charpoly=readlib(`DEtools/diffop/endomorphism_charpoly`),
	readlibs=readlib(`DEtools/diffop/readlibs`)
):

# Input a differential operator L
# Output: the eigenring
`DEtools/eigenring`:=proc(L,domain)
local d,v;
	option `Copyright (c) 1997 Waterloo Maple Inc. All rights reserved.`;
	d:=[args];
if indets(d,radical)<>{} then
	d:=procname(op(subs(readlib(`radnormal/radfield2`)(d,'v'),d)));
	RETURN(subs(eval(v),d))
fi;
	d:=`if`(nargs>1 and type(domain,list),domain,_Envdiffopdomain);
	if nops(d)<>2 then
		ERROR(`differential algebra not specified`)
	fi;
	_Envdiffopdomain:=d; # for the userinfo's in diffop.
	# load all files used by the eigenring code:
	readlibs(eigenring):
	# call the eigenring code
	subs(DF=d[1],x=d[2],
		eigenring(subs(d[1]=DF,d[2]=x,L),args[2..nargs]))
end:

# Input a differential operator L and a differential operator r: V(L) -> V(L)
# Output: the characteristic polynomial of this map r.
`DEtools/endomorphism_charpoly`:=proc(L,r,domain)
local d,v;
	option `Copyright (c) 1997 Waterloo Maple Inc. All rights reserved.`;
	d:=[args];
if indets(d,radical)<>{} then
	d:=procname(op(subs(readlib(`radnormal/radfield2`)(d,'v'),d)));
	RETURN(subs(eval(v),d))
fi;
	d:=`if`(nargs>2,domain,_Envdiffopdomain);
	if nops(d)<>2 then
		ERROR(`differential algebra not specified`)
	fi;
	# call the endomorphism_charpoly code
	subs(DF=d[1],x=d[2],
		endomorphism_charpoly(op(subs(d[1]=DF,d[2]=x,[L,r]))))
end:



#savelib('`DEtools/eigenring`','`DEtools/eigenring.m`'):
#savelib('`DEtools/endomorphism_charpoly`','`DEtools/endomorphism_charpoly.m`'):