libc.a reference
powi
Syntax
 #include <math.h>
double powi(double x, int iy);

Description
This function computes x^iy, where iy is an integer number.
It does so by an optimized sequence of squarings and multiplications.
For integer values of exponent, it is always faster to call powi
than to call pow
with the same arguments, even if iy has a
very large value. For small values of iy, powi
is
much faster than pow
.
Return Value
x raised to the iy power. If x and iy are both
zero, the return value is 1. If x is equal to zero, and iy
is negative, the return value is Inf
. This function never sets
errno
.
Portability