Data update

Task/Digital-root/Maxima/digital-root.maxima

@@ -0,0 +1,23 @@
+/* Function that returns a list of digits given a nonnegative integer */
+decompose(num) := block([digits, remainder],
+  digits: [],
+  while num > 0 do
+   (remainder: mod(num, 10),
+    digits: cons(remainder, digits),
+    num: floor(num/10)),
+  digits
+)$
+
+/* Function that given a positive integer returns the sum of their digits */
+auxdig(n):=block(decompose(n),apply("+",%%));
+
+/* Function that given a positive integer returns a list of two: the additive persistence and the digital root */
+digrt(n):=block([additive_persistence:0,digital_root:n],
+    while length(decompose(digital_root))>1 do (digital_root:auxdig(digital_root),additive_persistence:additive_persistence+1),
+    [additive_persistence,digital_root]);
+
+/* Examples */
+digrt(627615);
+digrt(39390);
+digrt(588225);
+digrt(393900588225);