1 .TH NAN 3
2 .SH NAME
3 NaN, Inf, isNaN, isInf \- not-a-number and infinity functions
4 .SH SYNOPSIS
5 .B #include <u.h>
6 .br
7 .B #include <libc.h>
8 .PP
9 .ta \w'\fLdouble 'u
10 .B
11 double	NaN(void)
12 .PP
13 .B
14 double	Inf(int)
15 .PP
16 .B
17 int	isNaN(double)
18 .PP
19 .B
20 int	isInf(double, int)
21 .SH DESCRIPTION
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
25 and division by zero.
26 Also, the library functions sometimes return them when
27 the arguments are not in the domain, or the result is
28 out of range.
29 .PP
30 .I NaN
31 returns a double that is not-a-number.
32 .I IsNaN
33 returns true if its argument is not-a-number.
34 .PP
35 .IR Inf ( i )
36 returns positive infinity if
37 .I i
38 is greater than or equal to zero,
39 else negative infinity.
40 .I IsInf
41 returns true if its first argument is infinity
42 with the same sign as the second argument.
43 .SH SOURCE
44 .B \*9/src/lib9/nan.c