cbrt, cbrtf, cbrtl

 

C

Language

headers

Type support

Dynamic memory management

Error handling

Program utilities

Variadic function support

Date and time utilities

Strings library

Algorithms

Numerics

Input/output support

Localization support

Thread support (C11)

Atomic operations (C11)

Technical Specifications

 

Numerics

Common mathematical functions

Floating-point environment

Complex number arithmetics

Random number generation

Type-generic math

 

Common mathematical functions

Functions
Basic operations
abslabsllabsimaxabs (C99) fabs divldivlldivimaxdiv (C99) fmod	remainder (C99) remquo (C99) fma (C99) fmax (C99) fmin (C99) fdim (C99) nannanfnanl (C99)(C99)(C99)
Exponential functions
exp exp2 (C99) expm1 (C99)	log log10 log1p (C99) log2 (C99)
Power functions
sqrt cbrt (C99)	hypot (C99) pow
Trigonometric and hyperbolic functions
sin cos tan asin acos atan atan2	sinh cosh tanh asinh (C99) acosh (C99) atanh (C99)
Error and gamma functions
erf (C99) erfc (C99)	lgamma (C99) tgamma (C99)
Nearest integer floating point operations
ceil floor roundlroundllround (C99)(C99)(C99)	trunc (C99) nearbyint (C99) rintlrintllrint (C99)(C99)(C99)
Floating point manipulation functions
ldexp scalbnscalbln (C99)(C99) ilogb (C99) logb (C99)	frexp modf nextafternexttoward (C99)(C99) copysign (C99)
Classification
fpclassify (C99) isfinite (C99) isinf (C99) isnan (C99) isnormal (C99) signbit (C99)	isgreater (C99) isgreaterequal (C99) isless (C99) islessequal (C99) islessgreater (C99) isunordered (C99)
Types
div_tldiv_tlldiv_timaxdiv_t (C99)(C99)	float_tdouble_t (C99)(C99)
Macro constants
HUGE_VALFHUGE_VALHUGE_VALL (C99)(C99) FP_FAST_FMAFFP_FAST_FMAFP_FAST_FMAL (C99)(C99)(C99) math_errhandlingMATH_ERRNOMATH_ERRNOEXCEPT (C99)(C99)(C99)	INFINITY (C99) NAN (C99) FP_ILOGB0FP_ILOGBNAN (C99)(C99) FP_NORMALFP_SUBNORMALFP_ZEROFP_INFINITEFP_NAN (C99)(C99)(C99)(C99)(C99)

 

Defined in header <math.h>
float       cbrtf( float arg );	(1)	(since C99)
double      cbrt( double arg );	(2)	(since C99)
long double cbrtl( long double arg );	(3)	(since C99)
Defined in header <tgmath.h>
#define cbrt( arg )	(4)	(since C99)

1-3) Computes the cubic root of arg.

4) Type-generic macro: If arg has type long double, cbrtl is called. Otherwise, if arg has integer type or the type double, cbrt is called. Otherwise, cbrtf is called.

Parameters

arg

-

floating point value

Return value

If no errors occur, the cubic root of arg (3√arg), is returned.

If a range error occurs due to underflow, the correct result (after rounding) is returned.

Error handling

Errors are reported as specified in math_errhandling.

If the implementation supports IEEE floating-point arithmetic (IEC 60559),

• if the argument is ±0 or ±∞, it is returned, unchanged
• if the argument is NaN, NaN is returned.

Notes

cbrt(arg) is not equivalent to pow(arg, 1.0/3) because pow cannot raise a negative base to a fractional exponent.

Example

Run this code

#include <stdio.h>
#include <math.h>
 
int main(void)
{
    // normal use
    printf("cbrt(729) = %f\n", cbrt(729));
    printf("cbrt(-0.125) = %f\n", cbrt(-0.125));
    // special values
    printf("cbrt(-0) = %f\n", cbrt(-0.0));
    printf("cbrt(+inf) = %f\n", cbrt(INFINITY));
}

Output:

cbrt(729) = 9.000000
cbrt(-0.125) = -0.500000
cbrt(-0) = -0.000000
cbrt(+inf) = inf

References

• C11 standard (ISO/IEC 9899:2011):

• 7.12.7.1 The cbrt functions (p: 247)

• 7.25 Type-generic math <tgmath.h> (p: 373-375)

• F.10.4.1 The cbrt functions (p: 524)

• C99 standard (ISO/IEC 9899:1999):

• 7.12.7.1 The cbrt functions (p: 228)

• 7.22 Type-generic math <tgmath.h> (p: 335-337)

• F.9.4.1 The cbrt functions (p: 460)

See also

powpowfpowl (C99)(C99)	computes a number raised to the given power (xy) (function)
sqrtsqrtfsqrtl (C99)(C99)	computes square root (√x) (function)
hypothypotfhypotl (C99)(C99)(C99)	computes square root of the sum of the squares of two given numbers (√x2 +y2 ) (function)
C++ documentation for cbrt