3 NaN, Inf, isNaN, isInf \- not-a-number and infinity functions
20 int isInf(double, int)
22 The IEEE floating point standard defines values called
23 `not-a-number' and positive and negative `infinity'.
24 These values can be produced by such things as overflow
26 Also, the library functions sometimes return them when
27 the arguments are not in the domain, or the result is
29 By default, manipulating these values may cause a floating point exception
30 on some processors but
34 can change that behavior.
37 returns a double that is not-a-number.
39 returns true if its argument is not-a-number.
42 returns positive infinity if
44 is greater than or equal to zero,
45 else negative infinity.
47 returns true if its first argument is infinity
48 with the same sign as the second argument.
50 .B /sys/src/libc/port/nan.c