cbrt - Man Page

cube root functions


This manual page is part of the POSIX Programmer's Manual. The Linux implementation of this interface may differ (consult the corresponding Linux manual page for details of Linux behavior), or the interface may not be implemented on Linux.


#include <math.h>

double cbrt(double x);
float cbrtf(float x);
long double cbrtl(long double x);


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.1-2017 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.

If x is NaN, a NaN shall be returned.

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


No errors are defined.

The following sections are informative.



Application Usage



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


See Also

The Base Definitions volume of POSIX.1-2017, <math.h>

Referenced By


2017 IEEE/The Open Group POSIX Programmer's Manual