rnrt stands for rational nth root. It is an experimental program used to compute a rational approximation to the nth root of any rational number.
The algorithm is simply based on a search in the Stern-Brocot tree and is currently written in Haskell. Implementations in other programming languages may come later.
This work was inspired by Norman Wildberger’s MathFoundations video series.
To get a rational approximation to the cubic root of 2 with an error less than 1/1000:
$ runhaskell Main.hs 3 2%1 1%1000 Rational approximation: 63 % 50 Decimal approximation: 1.26 Control: 2.000376
Note that the error is measured between the original number and the computed solution raised to the nth power. In the above example, the error is (2.000376 - 2.0) = 0.000376, which is less than 1/1000.
Copyright 2016 Sébastien Watteau
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