Data commit

Task/Mertens-function/Swift/mertens-function.swift

@@ -0,0 +1,41 @@
+import Foundation
+
+func mertensNumbers(max: Int) -> [Int] {
+    var mertens = Array(repeating: 1, count: max + 1)
+    for n in 2...max {
+        for k in 2...n {
+            mertens[n] -= mertens[n / k]
+        }
+    }
+    return mertens
+}
+
+let max = 1000
+let mertens = mertensNumbers(max: max)
+
+let count = 200
+let columns = 20
+print("First \(count - 1) Mertens numbers:")
+for i in 0..<count {
+    if i % columns > 0 {
+        print(" ", terminator: "")
+    }
+    print(i == 0 ? "  " : String(format: "%2d", mertens[i]), terminator: "")
+    if (i + 1) % columns == 0 {
+        print()
+    }
+}
+
+var zero = 0, cross = 0, previous = 0
+for i in 1...max {
+    let m = mertens[i]
+    if m == 0 {
+        zero += 1
+        if previous != 0 {
+            cross += 1
+        }
+    }
+    previous = m
+}
+print("M(n) is zero \(zero) times for 1 <= n <= \(max).")
+print("M(n) crosses zero \(cross) times for 1 <= n <= \(max).")