Initial data commit

Task/Cumulative-standard-deviation/Python/cumulative-standard-deviation-3.py

@@ -0,0 +1,25 @@
+>>> from math import sqrt
+>>> def sdcreator():
+	sum = sum2 = n = 0
+	def sd(x):
+		nonlocal sum, sum2, n
+
+		sum  += x
+		sum2 += x*x
+		n    += 1.0
+		return sqrt(sum2/n - sum*sum/n/n)
+	return sd
+
+>>> sd = sdcreator()
+>>> for value in (2,4,4,4,5,5,7,9):
+	print (value, sd(value))
+
+	
+2 0.0
+4 1.0
+4 0.942809041582
+4 0.866025403784
+5 0.979795897113
+5 1.0
+7 1.39970842445
+9 2.0