Data commit

Task/Cumulative-standard-deviation/Sidef/cumulative-standard-deviation-1.sidef

@@ -0,0 +1,22 @@
+class StdDevAccumulator(n=0, sum=0, sumofsquares=0) {
+  method <<(num) {
+    n += 1
+    sum += num
+    sumofsquares += num**2
+    self
+  }
+ 
+  method stddev {
+    sqrt(sumofsquares/n - pow(sum/n, 2))
+  }
+ 
+  method to_s {
+    self.stddev.to_s
+  }
+}
+ 
+var i = 0
+var sd = StdDevAccumulator()
+[2,4,4,4,5,5,7,9].each {|n|
+    say "adding #{n}: stddev of #{i+=1} samples is #{sd << n}"
+}

Task/Cumulative-standard-deviation/Sidef/cumulative-standard-deviation-2.sidef

@@ -0,0 +1,10 @@
+func stddev(x) {
+    static(num=0, sum=0, sum2=0)
+    num++
+    sqrt(
+        (sum2 += x**2) / num -
+        (((sum += x) / num)**2)
+    )
+}
+ 
+%n(2 4 4 4 5 5 7 9).each { say stddev(_) }