Initial data commit

Task/Cumulative-standard-deviation/Swift/cumulative-standard-deviation-1.swift

@@ -0,0 +1,28 @@
+import Darwin
+class stdDev{
+
+    var n:Double = 0.0
+    var sum:Double = 0.0
+    var sum2:Double = 0.0
+
+    init(){
+
+        let testData:[Double] = [2,4,4,4,5,5,7,9];
+        for x in testData{
+
+            var a:Double = calcSd(x)
+            println("value \(Int(x)) SD = \(a)");
+        }
+
+    }
+
+    func calcSd(x:Double)->Double{
+
+        n += 1
+        sum += x
+        sum2 += x*x
+        return sqrt( sum2 / n - sum*sum / n / n)
+    }
+
+}
+var aa = stdDev()

Task/Cumulative-standard-deviation/Swift/cumulative-standard-deviation-2.swift

@@ -0,0 +1,12 @@
+func standardDeviation(arr : [Double]) -> Double
+{
+    let length = Double(arr.count)
+    let avg = arr.reduce(0, { $0 + $1 }) / length
+    let sumOfSquaredAvgDiff = arr.map { pow($0 - avg, 2.0)}.reduce(0, {$0 + $1})
+    return sqrt(sumOfSquaredAvgDiff / length)
+}
+
+let responseTimes = [ 18.0, 21.0, 41.0, 42.0, 48.0, 50.0, 55.0, 90.0 ]
+
+standardDeviation(responseTimes) // 20.8742514835862
+standardDeviation([2,4,4,4,5,5,7,9]) // 2.0