"Source: Text/Commut/RngDiff.text";
"Line: 3466";
"Date: Thu Sep 25 14:47:46 2025";
"Main: Fri Sep 26 14:29:19 2025";
// original file: Text/Commut/RngDiff.text, line: 3466
// Example: H121E61 ()
print "Example: H121E61";
ei := GetEchoInput();
SetEchoInput(true);
F<z> := RationalDifferentialField(Rationals());
R<D> := DifferentialOperatorRing(F);
L := D^2+z*D-3*z^2;
npgon, op := NewtonPolygon(L, Zeros(1/z)[1]);
op;
Differential(Parent(op));
Valuation($1,Zeros(1/z)[1]);
assert $1 eq -1;
faces:= Faces(npgon);
faces;
_<T> := PolynomialRing(Rationals());
NewtonPolynomial(faces[1]);
SetEchoInput(ei);
