pow, powf

Статья
10/16/2008

Calculates x raised to the power of y.

double pow(
   double x,
   double y 
);
double pow(
   double x,
   int y
);  // C++ only
float pow(
   float x,
   float y 
);  // C++ only
float pow(
   float x,
   int y
);  // C++ only
long double pow(
   long double x,
   long double y
);  // C++ only
long double pow(
   long double x,
   int y
);  // C++ only
float powf(
   float x,
   float y 
);

Параметры

x
Base.
y
Exponent.

Возвращаемое значение

Returns the value of xy. No error message is printed on overflow or underflow.

Values of x and y	Return value of pow
x < > 0 and y = 0.0	1
x = 0.0 and y = 0.0	1
x = 0.0 and y < 0	INF

Заметки

The pow function computes x raised to the power of y.

pow does not recognize integral floating-point values greater than 264, such as 1.0E100.

pow has an implementation that uses Streaming SIMD Extensions 2 (SSE2). See _set_SSE2_enable for information and restrictions on using the SSE2 implementation.

C++ allows overloading, so you can call any of the various overloads of pow. In a C program, pow always takes two double values and returns a double value.

Visual C++ 2005 introduces a breaking change to better conform with the ISO standard. The pow(int, int) overload is no longer available. If you are using this overload, the compiler may emit C2668. To avoid this problem, cast the first parameter to double, float, or long double.

Требования

Routine	Required header
pow, powf	<math.h>

For additional compatibility information, see Compatibility in the Introduction.

Libraries

All versions of the C run-time libraries.

Пример

// crt_pow.c

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

int main( void )
{
   double x = 2.0, y = 3.0, z;

   z = pow( x, y );
   printf( "%.1f to the power of %.1f is %.1f\n", x, y, z );
}