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- .TH NAN 2
- .SH NAME
- NaN, Inf, isNaN, isInf \- not-a-number and infinity functions
- .SH SYNOPSIS
- .B #include <u.h>
- .br
- .B #include <libc.h>
- .PP
- .ta \w'\fLdouble 'u
- .B
- double NaN(void)
- .PP
- .B
- double Inf(int)
- .PP
- .B
- int isNaN(double)
- .PP
- .B
- int isInf(double, int)
- .SH DESCRIPTION
- 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.
- .PP
- .I NaN
- returns a double that is not-a-number.
- .I IsNaN
- returns true if its argument is not-a-number.
- .PP
- .IR Inf ( i )
- returns positive infinity if
- .I i
- is greater than or equal to zero,
- else negative infinity.
- .I IsInf
- returns true if its first argument is infinity
- with the same sign as the second argument.
- .SH SOURCE
- .B /sys/src/libc/port/nan.c
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