Comparing Double.NaN with itself

Question

I am stuck trying to find out why these two operations return different values:

1. Double.NaN == Double.NaN returns false
2. Do

Answer 1

Well, Oded's answer is great but I want to say something;

When I decompile Double.Equals() method, it seems like this;

public bool Equals(double obj)
{
    return ((obj == this) || (IsNaN(obj) && IsNaN(this)));
}

So since we have this = Double.NaN and obj = Double.NaN

(IsNaN(obj)) and (IsNaN(this)) returns `true`.

So basicly it is could return ((obj == this) || true

which is equvalent to

return ((obj == this) is true.