nan question

[bobef]

Hello,

I have a little question.
This program outputs gggg on dmd 1.21. Yes, I suck at math, but is this right (i.e. buggy) or nans must be compared another way?


===========================

import tango.io.Stdout;

void main()
{
	double a=double.nan;
	if(a==double.nan) Stdout("1\n");
	else Stdout("g\n");
	if(a is double.nan) Stdout("2\n");
	else Stdout("g\n");
	if(double.nan==double.nan) Stdout("3\n");
	else Stdout("g\n");
	if(double.nan is double.nan) Stdout("4\n");
	else Stdout("g\n");
}