/** Return this raised to an integer power.
* Implemented by repeated squaring and multiplication.
* If y < 0, returns div_inv of the result. */
public virtual Numeric power(IntNum y)
{
if (y.isNegative())
{
return(power(IntNum.neg(y)).div_inv());
}
Numeric pow2 = this;
Numeric r = null;
for (;;) // for (i = 0; ; i++)
{
// pow2 == x**(2**i)
// prod = x**(sum(j=0..i-1, (y>>j)&1))
if (y.isOdd())
{
r = r == null ? pow2 : r.mul(pow2); // r *= pow2
}
y = IntNum.shift(y, -1);
if (y.isZero())
{
break;
}
// pow2 *= pow2;
pow2 = pow2.mul(pow2);
}
return(r == null?mul_ident() : r);
}