cbrt, cbrtf, cbrtl
From cppreference.com
| Defined in header <math.h>
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float cbrtf( float arg );
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(1) | (since C99) |
double cbrt( double arg );
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(2) | (since C99) |
long double cbrtl( long double arg );
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(3) | (since C99) |
| Defined in header <tgmath.h>
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#define cbrt( arg )
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(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 (xy) (function) |
(C99)(C99) |
computes square root (√x) (function) |
(C99)(C99)(C99) |
computes square root of the sum of the squares of two given numbers (√x2 +y2 ) (function) |
C++ documentation for cbrt
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