This section describes some miscellaneous test functions on doubles.
Prototypes for these functions appear in `math.h'. These are BSD
functions, and thus are available if you define
-1if x represents negative infinity,
1if x represents positive infinity, and
x != xto get the same result).
infnanto decide what to return on occasion of an error. Its argument is an error code,
infnanreturns a suitable value to indicate this with.
-ERANGEis also acceptable as an argument, and corresponds to
-HUGE_VALas a value.
In the BSD library, on certain machines,
infnan raises a fatal
signal in all cases. The GNU library does not do likewise, because that
does not fit the ISO C specification.
Portability Note: The functions listed in this section are BSD extensions.
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