cbrt, cbrtf, cbrtl

From cppreference.com
< c ‎ | numeric ‎ | math
C
Numerics
Common mathematical functions
Types
Functions
Basic operations
(C99)
(C99)
(C99)
(C99)
(C99) (C99) (C99) (C23)
Maximum/minimum operations
Exponential functions
Power functions
cbrt
(C99)
(C23)
(C23)
Trigonometric and hyperbolic functions
Error and gamma functions
(C99)
(C99)
(C99)
(C99)
Nearest integer floating-point operations
(C99)
(C99) (C99) (C99)
(C23) (C23) (C23) (C23)
Floating-point manipulation functions
Narrowing operations
(C23)
(C23)
(C23)
(C23)
(C23)
(C23)
Quantum and quantum exponent functions
Decimal re-encoding functions
Total order and payload functions
Classification
Macro constants
Special floating-point values
Arguments and return values
Error handling
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 cube 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 cube 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 the rational number
1
3
is typically not equal to 1.0 / 3 and std::pow cannot raise a negative base to a fractional exponent. Moreover, cbrt ( arg ) usually gives more accurate results than pow ( arg, 1.0 / 3 ) (see example).

Example

Run this code 
#include <float.h>
#include <math.h>
#include <stdio.h>
 
int main(void)
{
    printf("Normal use:\n"
           "cbrt(729)      = %f\n", cbrt(729));
    printf("cbrt(-0.125)   = %f\n", cbrt(-0.125));
    printf("Special values:\n"
           "cbrt(-0)       = %f\n", cbrt(-0.0));
    printf("cbrt(+inf)     = %f\n", cbrt(INFINITY));
    printf("Accuracy:\n"
           "cbrt(343)      = %.*f\n", DBL_DECIMAL_DIG, cbrt(343));
    printf("pow(343,1.0/3) = %.*f\n", DBL_DECIMAL_DIG, pow(343, 1.0/3));
}

Possible output: 

Normal use:
cbrt(729)      = 9.000000
cbrt(-0.125)   = -0.500000
Special values:
cbrt(-0)       = -0.000000
cbrt(+inf)     = inf
Accuracy:
cbrt(343)      = 7.00000000000000000
pow(343,1.0/3) = 6.99999999999999911

References

  • C23 standard (ISO/IEC 9899:2024):
  • 7.12.7.1 The cbrt functions (p: TBD)
  • 7.25 Type-generic math <tgmath.h> (p: TBD)
  • F.10.4.1 The cbrt functions (p: TBD)
  • C17 standard (ISO/IEC 9899:2018):
  • 7.12.7.1 The cbrt functions (p: 180-181)
  • 7.25 Type-generic math <tgmath.h> (p: 272-273)
  • F.10.4.1 The cbrt functions (p: 381-)
  • 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

(C99) (C99)
computes a number raised to the given power ( x y )
(function)
(C99) (C99)
computes square root ( √ x )
(function)
(C99) (C99) (C99)
computes square root of the sum of the squares of two given numbers ( √ x 2 +y 2 )
(function)
C++ documentation for cbrt
Retrieved from " https://en.cppreference.com/mwiki/index.php?title=c/numeric/math/cbrt&oldid=172001 "