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NAN | Constant (Pseudo-constant) |
math.h, timath.h |
A constant defining an undefined value.
NAN
is an acronyme of "Not a Number". TIOS generates NAN
when nothing can be deduced
about the magnitude of the result (for example, when dividing zero by zero, or when
substracting two infinities of the same sign). Also, TIOS generates NAN
when the
argument of a function is out of legal range, excluding values of the argument which
produces infinity results. For example, log will produce NAN
when the
argument is negative, but when the argument is zero, the result is
NEGATIVE_INF.
NAN
also belongs to the class of "transfinite" numbers (see is_transfinite).
Use is_nan to check whether a value is NAN
. This is a common
method to check in run time whether the arguments of the called math functions was legal.