Computes power.
#include <math.h> float powf (x, y) float x; float y; long double powl (x, y) long double x, y; double pow (x, y) double x, y;
The powf, powl, and pow subroutines compute the value of x raised to the power y, x y. If x is negative, the application ensures that y is an integer value.
An application wishing to check for error situations should set errno to zero and call feclearexcept(FE_ALL_EXCEPT) before calling these subroutines. Upon return, if errno is nonzero or fetestexcept(FE_INVALID | FE_DIVBYZERO | FE_OVERFLOW | FE_UNDERFLOW) is nonzero, an error has occurred.
| x | Specifies the value of the base. |
| y | Specifies the value of the exponent. |
Upon successful completion, the pow, powf and powl subroutines return the value of x raised to the power y.
For finite values of x < 0, and finite non-integer values of y, a domain error occurs and a NaN is returned.
If the correct value would cause overflow, a range error occurs and the pow, powf, and powl subroutines return HUGE_VAL, HUGE_VALF, and HUGE_VALL, respectively.
If the correct value would cause underflow, and is not representable, a range error may occur, and 0.0 is returned.
If x or y is a NaN, a NaN is returned (unless specified elsewhere in this description).
For any value of y (including NaN), if x is +1, 1.0 is returned.
For any value of x (including NaN), if y is ±0, 1.0 is returned.
For any odd integer value of y>0, if x is ±0, ±0 is returned.
For y > 0 and not an odd integer, if x is ±0, +0 is returned.
If x is -1, and y is ±Inf, 1.0 is returned.
For |x<1, if y is -Inf, +Inf is returned.
For |x>1, if y is -Inf, +0 is returned.
For |x<1, if y is +Inf, +0 is returned.
For |x>1, if y is +Inf, +Inf is returned.
For y an odd integer < 0, if x is -Inf, -0 is returned.
For y < 0 and not an odd integer, if x is -Inf, +0 is returned.
For y an odd integer > 0, if x is -Inf, -Inf is returned.
For y > 0 and not an odd integer, if x is -Inf, +Inf is returned.
For y <0, if x is +Inf, +0 is returned.
For y >0, if x is +Inf, +Inf is returned.
For y an odd integer < 0, if x is ±0, a pole error occurs and ±HUGE_VAL, ±HUGE_VALF, and ±HUGE_VALL is returned for pow, powf, and powl, respectively.
For y < 0 and not an odd integer, if x is ±0, a pole error occurs and HUGE_VAL, HUGE_VALF and HUGE_VALL is returned for pow, powf, and powl, respectively.
If the correct value would cause underflow, and is representable, a range error may occur and the correct value is returned.
When using the libm.a library:
| pow | If the correct value overflows, the powsubroutine returns a HUGE_VAL value and sets errno to ERANGE. If the x parameter is negative and the y parameter is not an integer, the pow subroutine returns a NaNQ value and sets errno to EDOM. If x=0 and the y parameter is negative, the pow subroutine returns a HUGE_VAL value but does not modify errno. |
| powl | If the correct value overflows, the powlsubroutine returns a HUGE_VAL value and sets errno to ERANGE. If the x parameter is negative and the y parameter is not an integer, the powl subroutine returns a NaNQ value and sets errno to EDOM. If x=0 and the y parameter is negative, the powl subroutine returns a HUGE_VAL value but does not modify errno. |
When using libmsaa.a(-lmsaa):
| pow | If x=0 and the y parameter
is not positive, or if the x parameter is negative
and the y parameter is not an integer, the pow subroutine returns 0 and sets errno to EDOM. In these cases a message indicating DOMAIN error is
output to standard error. When the correct value for the pow subroutine would overflow or underflow, the pow subroutine returns:
+HUGE_VAL OR -HUGE_VAL OR 0 When using either the libm.a library or the libsaa.a library: |
| powl | If the correct value overflows, powl returns HUGE_VAL and errno to ERANGE. If x is negative and y is not an integer, powl returns NaNQ and sets errno to EDOM. If x = zero and y is negative, powl returns a HUGE_VAL value but does not modify errno. |
exp, expf, or expl Subroutine, feclearexcept Subroutine, fetestexcept Subroutine, and class, _class, finite, isnan, or unordered Subroutines.
math.h in AIX 5L Version 5.2 Files Reference.