what a glitch!!
in BOL it says that SQRT ( float_expression )
and float could be, as definition of float,
float - 1.79E+308 to -2.23E-308, 0 and 2.23E-308 to 1.79E+308
so, where it says that the argument of SQRT should be not negative!???
In Theory, theory and practice are the same...In practice, they are not.