The Open Group Base Specifications Issue 7
IEEE Std 1003.1-2008, 2016 Edition
Copyright © 2001-2016 The IEEE and The Open Group

#### NAME

> cbrt, cbrtf, cbrtl - cube root functions

#### SYNOPSIS

> ``#include <math.h>
> double cbrt(double` x`);
> float cbrtf(float` x`);
> long double cbrtl(long double` x`);
> ``

#### DESCRIPTION

> [CX] The functionality described on this reference page is aligned with the ISO C standard. Any conflict between the requirements described here and the ISO C standard is unintentional. This volume of POSIX.1-2008 defers to the ISO C standard.

> These functions shall compute the real cube root of their argument x.

#### RETURN VALUE

> Upon successful completion, these functions shall return the cube root of x.

> [MX] If x is NaN, a NaN shall be returned.

> If x is ±0 or ±Inf, x shall be returned.

#### ERRORS

> No errors are defined.

The following sections are informative.

#### EXAMPLES

> None.

#### APPLICATION USAGE

> None.

#### RATIONALE

> For some applications, a true cube root function, which returns negative results for negative arguments, is more appropriate than pow(x, 1.0/3.0), which returns a NaN for x less than 0.

#### FUTURE DIRECTIONS

> None.

#### SEE ALSO

> XBD <math.h>

#### CHANGE HISTORY

> First released in Issue 4, Version 2.

#### Issue 5

> Moved from X/OPEN UNIX extension to BASE.

#### Issue 6

> The cbrt() function is no longer marked as an extension.

> The cbrtf() and cbrtl() functions are added for alignment with the ISO/IEC 9899:1999 standard.

> The DESCRIPTION, RETURN VALUE, ERRORS, and APPLICATION USAGE sections are revised to align with the ISO/IEC 9899:1999 standard.

> IEC 60559:1989 standard floating-point extensions over the ISO/IEC 9899:1999 standard are marked.

End of informative text.

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