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.1-2024 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.
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 (“ISO C99”) standard.
The DESCRIPTION, RETURN VALUE, ERRORS, and APPLICATION USAGE sections are revised to align with the ISO/IEC 9899:1999 (“ISO C99”) standard.
IEC 60559:1989 standard floating-point extensions over the ISO/IEC 9899:1999 (“ISO C99”) standard are marked.