public Rational Root(BigInteger r)
{
/* test for overflow */
if (r.CompareTo(MaxInt32) == 1)
{
throw new FormatException("Root " + r + " too large.");
}
if (r.CompareTo(MinInt32) == -1)
{
throw new FormatException("Root " + r + " too small.");
}
int rthroot = r.ToInt32();
/* cannot pull root of a negative value with even-valued root */
if (CompareTo(Zero) == -1 && (rthroot % 2) == 0)
{
throw new FormatException("Negative basis " + ToString() + " with odd root " + r);
}
/* extract a sign such that we calculate |n|^(1/r), still r carrying any sign
*/
bool flipsign = (CompareTo(Zero) == -1 && (rthroot % 2) != 0);
/* delegate the main work to ifactor#root()
*/
var num = new IFactor(Numerator.Abs());
var deno = new IFactor(Denominator);
Rational resul = num.Root(rthroot).Divide(deno.Root(rthroot));
return(flipsign ? resul.Negate() : resul);
}
private void GrowTo(int n)
{
/* extend the internal list if needed. Size to be 2 for n<=1, 3 for n<=2 etc.
*/
while (factors.Count <= n)
{
int lastn = factors.Count - 1;
var nextn = new IFactor(lastn + 1);
factors.Add(factors[lastn].Multiply(nextn));
}
}