NaN, Inf, isNaN, isInf – not–a–number and infinity functions|
int isInf(double, int)
The IEEE floating point standard defines values called `not–a–number'
and positive and negative `infinity'. These values can be produced
by such things as overflow and division by zero. Also, the library
functions sometimes return them when the arguments are not in
the domain, or the result is out of range. By
default, manipulating these values may cause a floating point
exception on some processors but setfcr (see getfcr(2)) can change
that behavior. |
NaN returns a double that is not–a–number. IsNaN returns true if its argument is not–a–number.
Inf(i) returns positive infinity if i is greater than or equal
to zero, else negative infinity. IsInf returns true if its first
argument is infinity with a sign matching the second argument.
A zero sign matches both negative and positive infinities.