"Source: Text/Commut/RngDiff.text";
"Line: 2178";
"Date: Thu Sep 25 14:47:46 2025";
"Main: Fri Sep 26 14:29:19 2025";
// original file: Text/Commut/RngDiff.text, line: 2178
// Example: H121E39 ()
print "Example: H121E39";
ei := GetEchoInput();
SetEchoInput(true);
F<z> := RationalDifferentialField(Rationals());
R<D> := DifferentialOperatorRing(F);
(z*D-1)*(D+1);
(D+1)*(z*D-1);
(D-1/z)^2;
SetEchoInput(ei);
