Data update

Task/Arithmetic-derivative/Lua/arithmetic-derivative.lua

@@ -0,0 +1,25 @@
+do    local function lagarias (n) -- Lagarias arithmetic derivative
+           if n < 0
+           then return -lagarias (-n)
+           elseif n == 0 or n == 1
+           then return 0
+           else local function smallPf (j, k) -- Smallest prime factor
+                    if j % k == 0 then return k else return smallPf (j, k + 1) end
+                end
+                local f = smallPf (n, 2) local q = math.floor (n / f)
+                if q == 1
+                then return 1
+                else return q * lagarias (f) + f * lagarias (q)
+                end
+           end
+      end
+      for n = -99,100
+      do io.write (string.format("%6d", lagarias (n)))
+         if n % 10 == 0 then io.write ("\n") end
+      end
+      io.write ("\n")
+      for n = 1,17     -- 18, 19 and 20 would overflow
+      do local m = 10 ^ n
+         io.write ("D(", string.format ("%d", m), ") / 7 = ", math.floor (lagarias (m) / 7), "\n")
+      end
+end