testValues:=T(
   T(100000000000000.01,100000000000000.011),
   T(100.01, 100.011),
   T(10000000000000.001 / 10000.0, 1000000000.0000001),
   T(0.001, 0.0010000001),
   T(0.00000000000000000101, 0.0),
   T(  (2.0).sqrt()*(2.0).sqrt(),  2.0),
   T( -(2.0).sqrt()*(2.0).sqrt(), -2.0),
   T(100000000000000003.0, 100000000000000004.0),
   T(3.14159265358979323846, 3.14159265358979324)
);

tolerance:=-1e-9;	// <0 for relative comparison
foreach x,y in (testValues){
   maybeNot:=( if(x.closeTo(y,tolerance)) " \u2248" else "!\u2248" );
   println("% 25.19g %s %- 25.19g  %g".fmt(x,maybeNot,y, (x-y).abs()));
}