Version 6 of NaN

[Replace this comment with an explanation of the return value of NaN that occasionally occurs within Tcl]

RS 2007-02-23: NaN is "Not a Number", a sort-of valid floating point value from Tcl 8.5. Here's experiments:

 (bin) 13 % set y [expr sqrt(-1)]
 -NaN
 (bin) 14 % expr {$y == $y} ;# the only value that is not equal to itself :^)
 0
 (bin) 15 % expr {$y eq $y}
 1

male 2007-02-23: Sorry, but using tclkit(sh)? 8.5a4 ...

 % expr {sqrt(-1)}
 domain error: argument not in valid range

RS I used tclkit 8.5a4 as well, on Win XP. So the patchlevel doesn't yet tell the full story :( Do the Inf examples work for you?