Initial data commit

Task/Totient-function/Factor/totient-function.factor

@@ -0,0 +1,26 @@
+USING: combinators formatting io kernel math math.primes.factors
+math.ranges sequences ;
+IN: rosetta-code.totient-function
+
+: Φ ( n -- m )
+    {
+        { [ dup 1 < ] [ drop 0 ] }
+        { [ dup 1 = ] [ drop 1 ] }
+        [
+            dup unique-factors
+            [ 1 [ 1 - * ] reduce ] [ product ] bi / *
+        ]
+    } cond ;
+
+: show-info ( n -- )
+    [ Φ ] [ swap 2dup - 1 = ] bi ", prime" "" ?
+    "Φ(%2d) = %2d%s\n" printf ;
+
+: totient-demo ( -- )
+    25 [1,b] [ show-info ] each nl 0 100,000 [1,b] [
+        [ dup Φ - 1 = [ 1 + ] when ]
+        [ dup { 100 1,000 10,000 100,000 } member? ] bi
+        [ dupd "%4d primes <= %d\n" printf ] [ drop ] if
+    ] each drop ;
+
+MAIN: totient-demo