public override Numeric power(IntNum y)
{
if (isOne())
return this;
if (isMinusOne())
return y.isOdd () ? this : IntNum.one ();
if (y.words == null && y.ival >= 0)
return power (this, y.ival);
if (isZero())
return y.isNegative () ? RatNum.infinity(-1) : (RatNum) this;
return base.power (y);
}
/** 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;
}