---
name: "infnan"
section: "3"
platform: "linux"
package: "manpages-dev"
version: "4.10-2"
release: "Debian 9 (Stretch)"
platforms: ["linux"]
url: "https://new.carta.tech/infnan"
---

# infnan(3)

deal with infinite or not-a-number (NaN) result

## NAME

infnan - deal with infinite or not-a-number (NaN) result

## SYNOPSIS

```
#include <math.h>

double infnan(int error);
```

Link with *-lm*.

## DESCRIPTION

The **infnan**() function returns a suitable value for infinity and "not-a-number" (NaN) results. The value of *error* can be **ERANGE** to represent infinity or anything else to represent NaN. *errno* is also set.

## RETURN VALUE

If *error* is **ERANGE** (Infinity), **HUGE\_VAL** is returned.

If *error* is -**ERANGE** (-Infinity), -**HUGE\_VAL** is returned.

If *error* is anything else, NAN is returned.

## ERRORS

- **EDOM**

  The value of *error* is "not-a-number" (NaN).

- **ERANGE**

  The value of *error* is positive infinity or negative infinity.

## CONFORMING TO

4\.3BSD.

## NOTES

This obsolete function was provided in libc4 and libc5, but is not available in glibc2.

## COLOPHON

This page is part of release 4.10 of the Linux *man-pages* project. A description of the project, information about reporting bugs, and the latest version of this page, can be found at https://www.kernel.org/doc/man-pages/.