23 lines
413 B
Python
23 lines
413 B
Python
>>> from math import sqrt
|
|
>>> def sd(x):
|
|
sd.sum += x
|
|
sd.sum2 += x*x
|
|
sd.n += 1.0
|
|
sum, sum2, n = sd.sum, sd.sum2, sd.n
|
|
return sqrt(sum2/n - sum*sum/n/n)
|
|
|
|
>>> sd.sum = sd.sum2 = sd.n = 0
|
|
>>> for value in (2,4,4,4,5,5,7,9):
|
|
print (value, sd(value))
|
|
|
|
|
|
(2, 0.0)
|
|
(4, 1.0)
|
|
(4, 0.94280904158206258)
|
|
(4, 0.8660254037844386)
|
|
(5, 0.97979589711327075)
|
|
(5, 1.0)
|
|
(7, 1.3997084244475311)
|
|
(9, 2.0)
|
|
>>>
|