LetsLet's look at the following example.
Ordering[{0, 20 Sqrt[5], 40 Sqrt[5], 20 Sqrt[5], 20 Sqrt[10]} // N]
which gives the right answer
{1, 2, 4, 5, 3}
but if one removes the N
, one gets the wrong answer
Ordering[{0, 20 Sqrt[5], 40 Sqrt[5], 20 Sqrt[5], 20 Sqrt[10]}]
{1, 2, 4, 3, 5}
Is it a bug?