An implementation of the shifting n-th root algorithm for BigDecimal.
An implementation of the shifting n-th root algorithm for BigDecimal. For the BigDecimal a, this is guaranteed to be accurate up to the precision specified in ctxt.
See http://en.wikipedia.org/wiki/Shifting_nth_root_algorithm
A (positive if k % 2 == 0) BigDecimal.
A positive Int greater than 1.
The MathContext to bound the precision of the result.
returns A BigDecimal approximation to the k-th root of a.