RosettaCodeData/Task/Nth-root/Picat/nth-root.picat
2023-07-01 13:44:08 -04:00

30 lines
563 B
Text

go =>
L = [[2,2],
[34,5],
[34**5,5],
[7131.5**10],
[7,0.5],
[1024,10],
[5642, 125]
],
foreach([A,N] in L)
R = nthroot(A,N),
printf("nthroot(%8w,%8w) %20w (check: %w)\n",A,N,R,A**(1/N))
end,
nl.
%
% x^n = a
%
% Given a and n, find x (to Precision)
%
nthroot(A,N) = nthroot(A,N,0.000001).
nthroot(A,N,Precision) = X1 =>
NF = N * 1.0, % float version of N
X0 = A / NF,
X1 = 1.0,
do
X0 := X1,
X1 := (1.0 / NF)*((NF - 1.0)*X0 + (A / (X0 ** (NF - 1))))
while( abs(X0-X1) > Precision).