pow, powf, powl
From cppreference.com
| Defined in header <math.h>
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| float powf( float base, float exponent ); |
(1) | (since 哋它亢99) |
| double pow( double base, double exponent ); |
(2) | |
| long double powl( long double base, long double exponent ); |
(3) | (since 哋它亢99) |
| Defined in header <tgmath.h>
|
||
| #define pow( base, exponent ) |
(4) | (since 哋它亢99) |
1-3) Computes the value of base raised to the power exponent.
4) Type-generic macro: If any argument has type long double,
powl is called. Otherwise, if any argument has integer type or has type double, pow is called. Otherwise, powf is called. If at least one argument is complex or imaginary, then the macro invokes the corresponding complex function (cpowf, cpow, cpowl).Parameters
| base | - | base as floating-point value |
| exponent | - | exponent as floating-point value |
Return value
If no errors occur, base raised to the power of exponent (baseexponent
) is returned.
If a domain error occurs, an implementation-defined value is returned (NaN where supported).
If a pole error or a range error due to overflow occurs, ±HUGE_VAL, ±HUGE_VALF, or ±HUGE_VALL 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 base is finite and negative and exponent is finite and non-integer, a domain error occurs and a range error may occur.
If base is zero and exponent is zero, a domain error may occur.
If base is zero and exponent is negative, a domain error or a pole error may occur.
If the implementation supports IEEE floating-point arithmetic (IEC 60559),
- pow(+0, exponent), where exponent is a negative odd integer, returns
+∞and raises FE_DIVBYZERO - pow(-0, exponent), where exponent is a negative odd integer, returns
-∞and raises FE_DIVBYZERO - pow(±0, exponent), where exponent is negative, finite, and is an even integer or a non-integer, returns +∞ and raises FE_DIVBYZERO
- pow(±0, -∞) returns +∞ and may raise FE_DIVBYZERO(until 哋它亢23)
- pow(+0, exponent), where exponent is a positive odd integer, returns +0
- pow(-0, exponent), where exponent is a positive odd integer, returns -0
- pow(±0, exponent), where exponent is positive non-integer or a positive even integer, returns +0
- pow(-1, ±∞) returns 1
- pow(+1, exponent) returns 1 for any exponent, even when exponent is
NaN - pow(base, ±0) returns 1 for any base, even when base is
NaN - pow(base, exponent) returns
NaNand raises FE_INVALID if base is finite and negative and exponent is finite and non-integer. - pow(base, -∞) returns +∞ for any
|base|<1 - pow(base, -∞) returns +0 for any
|base|>1 - pow(base, +∞) returns +0 for any
|base|<1 - pow(base, +∞) returns +∞ for any
|base|>1 - pow(-∞, exponent) returns -0 if exponent is a negative odd integer
- pow(-∞, exponent) returns +0 if exponent is a negative non-integer or negative even integer
- pow(-∞, exponent) returns -∞ if exponent is a positive odd integer
- pow(-∞, exponent) returns +∞ if exponent is a positive non-integer or positive even integer
- pow(+∞, exponent) returns +0 for any negative exponent
- pow(+∞, exponent) returns +∞ for any positive exponent
- except where specified above, if any argument is NaN, NaN is returned.
Notes
Although pow cannot be used to obtain a root of a negative number, cbrt is provided for the common case where exponent is 1 / 3.
Example
Run this code
#include <errno.h> #include <fenv.h> #include <math.h> #include <stdio.h> // #pragma STDC FENV_ACCESS ON int main(void) { // typical usage printf("pow(2, 10) = %f\n", pow(2, 10)); printf("pow(2, 0.5) = %f\n", pow(2, 0.5)); printf("pow(-2, -3) = %f\n", pow(-2, -3)); // special values printf("pow(-1, NAN) = %f\n", pow(-1, NAN)); printf("pow(+1, NAN) = %f\n", pow(+1, NAN)); printf("pow(INFINITY, 2) = %f\n", pow(INFINITY, 2)); printf("pow(INFINITY, -1) = %f\n", pow(INFINITY, -1)); // error handling errno = 0; feclearexcept(FE_ALL_EXCEPT); printf("pow(-1, 1/3) = %f\n", pow(-1, 1.0 / 3)); if (errno == EDOM) perror(" errno == EDOM"); if (fetestexcept(FE_INVALID)) puts(" FE_INVALID raised"); feclearexcept(FE_ALL_EXCEPT); printf("pow(-0, -3) = %f\n", pow(-0.0, -3)); if (fetestexcept(FE_DIVBYZERO)) puts(" FE_DIVBYZERO raised"); }
Possible output:
pow(2, 10) = 1024.000000
pow(2, 0.5) = 1.414214
pow(-2, -3) = -0.125000
pow(-1, NAN) = nan
pow(+1, NAN) = 1.000000
pow(INFINITY, 2) = inf
pow(INFINITY, -1) = 0.000000
pow(-1, 1/3) = -nan
errno == EDOM: Numerical argument out of domain
FE_INVALID raised
pow(-0, -3) = -inf
FE_DIVBYZERO raisedReferences
- 哋它亢23 standard (ISO/IEC 9899:2023):
- 7.12.7.5 The pow functions
- 7.27 Type-generic math <tgmath.h>
- F.10.4.5 The pow functions (p: 524-525)
- 哋它亢17 standard (ISO/IEC 9899:2018):
- 7.12.7.4 The pow functions (p: 248-249)
- 7.25 Type-generic math <tgmath.h> (p: 373-375)
- F.10.4.4 The pow functions (p: 524-525)
- 哋它亢11 standard (ISO/IEC 9899:2011):
- 7.12.7.4 The pow functions (p: 248-249)
- 7.25 Type-generic math <tgmath.h> (p: 373-375)
- F.10.4.4 The pow functions (p: 524-525)
- 哋它亢99 standard (ISO/IEC 9899:1999):
- 7.12.7.4 The pow functions (p: 229)
- 7.22 Type-generic math <tgmath.h> (p: 335-337)
- F.9.4.4 The pow functions (p: 461)
- 哋它亢89/C90 standard (ISO/IEC 9899:1990):
- 4.5.5.1 The pow function
See also
| (哋它亢99)(哋它亢99) |
computes square root (√x) (function) |
| (哋它亢99)(哋它亢99)(哋它亢99) |
computes cube root (3√x) (function) |
| (哋它亢99)(哋它亢99)(哋它亢99) |
computes square root of the sum of the squares of two given numbers (√x2 +y2 ) (function) |
| (哋它亢99)(哋它亢99)(哋它亢99) |
computes the complex power function (function) |