powr

Compute the value of x raised to the power of y, where x ≥ 0.

Interface Definition

C interface:

float powrf(float x, float y);

double powr(double x, double y);

Parameters

Parameter	Type	Description	Input/Output
x	For powrf, x is of single-precision floating-point type. For powr, x is of double-precision floating-point type.	Floating-point value of the input data.	Input
y	For powrf, y is of single-precision floating-point type. For powr, y is of double-precision floating-point type.	Floating-point value of the input data.	Input

Return Value

If x is greater than or equal to 0 and y is not a special value, the result of x raised to the power of y is returned. Value range: (0, +INF)
If x is less than 0, the return value is NaN.

Other combinations of special values are listed in the following table.

Input Value (x)	Input Value (y)	Output Value (result)
+0	+0	+1
+0	-0	+1
+0	inf	+0
+0	-inf	inf
+0	SNaN	NaN
+0	–SNaN	NaN
+0	QNaN	NaN
+0	–QNaN	NaN
-0	+0	+1
-0	-0	+1
-0	inf	+0
-0	-inf	inf
-0	SNaN	NaN
-0	–SNaN	NaN
-0	QNaN	NaN
-0	–QNaN	NaN
inf	+0	+1
inf	-0	+1
inf	inf	inf
inf	-inf	+0
inf	SNaN	NaN
inf	–SNaN	NaN
inf	QNaN	NaN
inf	–QNaN	NaN
-inf	+0	NaN
-inf	-0	NaN
-inf	inf	NaN
-inf	-inf	NaN
-inf	SNaN	NaN
-inf	–SNaN	NaN
-inf	QNaN	NaN
-inf	–QNaN	NaN
SNaN	+0	+1
SNaN	-0	+1
SNaN	inf	NaN
SNaN	-inf	NaN
SNaN	SNaN	NaN
SNaN	–SNaN	NaN
SNaN	QNaN	NaN
SNaN	–QNaN	NaN
–SNaN	+0	+1
–SNaN	-0	+1
–SNaN	inf	NaN
–SNaN	-inf	NaN
–SNaN	SNaN	NaN
–SNaN	–SNaN	NaN
–SNaN	QNaN	NaN
–SNaN	–QNaN	NaN
QNaN	+0	+1
QNaN	-0	+1
QNaN	inf	NaN
QNaN	-inf	NaN
QNaN	SNaN	NaN
QNaN	–SNaN	NaN
QNaN	QNaN	NaN
QNaN	–QNaN	NaN
–QNaN	+0	+1
–QNaN	-0	+1
–QNaN	inf	NaN
–QNaN	-inf	NaN
–QNaN	SNaN	NaN
–QNaN	–SNaN	NaN
–QNaN	QNaN	NaN
–QNaN	–QNaN	NaN

Dependency

C: "km.h"

Example

C interface:

    // typical usage
    double x1 = 0.0, x2 = -0.0, x3 = 1.5, x4 = -2.5;
    // special handing
    double a = INFINITY, b = -INFINITY, c = NAN;
    // print result
    printf("powr(0.0, -0.0) = %.15f\n", powr(x1, x2));
    printf("powr(-0.0, 0.0) = %.15f\n", powr(x2, x1));
    printf("powr(1.5, 1.5) = %.15f\n", powr(x3, x3));
    printf("powr(-2.5, 1.5) = %.15f\n", powr(x4, x3));
    printf("powr(INFINITY, 1.5) = %.15f\n", powr(a, x3));
    printf("powr(-INFINITY, 1.5) = %.15f\n", powr(b, x3));
    printf("powr(NAN, NAN) = %.15f\n", powr(c, c));
    return 0;

    /*
     * powr(0.0, -0.0) = 1.000000000000000
     * powr(-0.0, 0.0) = 1.000000000000000
     * powr(1.5, 1.5) = 1.837117307087384
     * powr(-2.5, 1.5) = nan
     * powr(INFINITY, 1.5) = inf
     * powr(-INFINITY, 1.5) = nan
     * powr(NAN, NAN) = nan
     */

Parent topic: Function Syntax