Data commit

Task/Prime-decomposition/Picat/prime-decomposition.picat

@@ -0,0 +1,39 @@
+go =>
+  % Checking 2**prime-1
+  foreach(P in primes(60))
+     Factors = factors(2**P-1),
+     println([n=2**P-1,factors=Factors])
+  end,
+  nl,
+  % Testing a larger number
+  println(factors(1361129467683753853853498429727072845823)),
+  nl.
+
+%
+% factors of N
+%
+factors(N) = Factors =>
+   Factors = [],
+   M = N,
+   while (M mod 2 == 0)
+      Factors := Factors ++ [2],
+      M := M div 2
+   end,
+   T = 3,
+   while (M > 1, T < 1+(sqrt(M)))
+      if M mod T == 0 then
+         [Divisors, NewM] = alldivisorsM(M, T),
+         Factors := Factors ++ Divisors,
+         M := NewM
+      end,
+      T := T + 2
+   end,
+   if M > 1 then Factors := Factors ++ [M] end.
+
+alldivisorsM(N,Div) = [Divisors,M] =>
+   M = N,
+   Divisors = [],
+   while (M mod Div == 0)
+      Divisors := Divisors ++ [Div],
+      M := M div Div
+   end.