Namespaces
Variants
Views
Actions

cbrt, cbrtf, cbrtl

From cppreference.com
< c‎ | numeric‎ | math
 
 
 
Common mathematical functions
Types
(C99)(C99)    

(C99)(C99)    

Functions
Basic operations
(C99)
(C99)
(C99)
(C99)(C99)(C99)(C23)
Maximum/minimum operations
(C99)
(C23)    
Exponential functions
(C23)
(C99)
(C99)
(C23)
(C23)
(C99)
(C99)(C23)
(C23)
(C23)
Power functions
cbrt
(C99)
(C23)
(C23)
(C99)
(C23)
(C23)
Trigonometric and hyperbolic functions
(C23)
(C23)
(C23)
(C23)
(C99)
(C99)
(C99)
Error and gamma functions
(C99)
(C99)
(C99)
(C99)
Nearest integer floating-point operations
(C99)(C99)(C99)
(C99)
(C99)(C99)(C99)
(C23)(C23)(C23)(C23)
Floating-point manipulation functions
(C99)(C99)
(C99)(C23)
(C99)
Narrowing operations
(C23)
(C23)
(C23)
(C23)
(C23)
(C23)
Quantum and quantum exponent functions
Decimal re-encoding functions
Total order and payload functions
Classification
(C99)
(C99)
(C99)
(C23)
Macro constants
Special floating-point values
(C99)(C23)
Arguments and return values
(C99)(C99)(C99)(C99)(C99)    
Error handling
(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 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.

Contents

[edit] Parameters

arg - floating point value

[edit] Return value

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

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

[edit] 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.

[edit] 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).

[edit] Example

#include <stdio.h>
#include <float.h>
#include <math.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

[edit] References

  • 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)

[edit] See also

(C99)(C99)
computes a number raised to the given power (xy)
(function) [edit]
(C99)(C99)
computes square root (x)
(function) [edit]
(C99)(C99)(C99)
computes square root of the sum of the squares of two given numbers (x2
+y2
)
(function) [edit]