import math
proc nthroot(a, n): float =
var n = float(n)
result = a
var x = a / n
while abs(result-x) > 10e-15:
x = result
result = (1.0/n) * (((n-1)*x) + (a / pow(x, n-1)))
echo nthroot(34.0, 5)
echo nthroot(42.0, 10)
echo nthroot(5.0, 2)