StandardDeviation¶

Returns the standard deviation of a list.

$ wo 'StandardDeviation[{}]'
StandardDeviation[{}]

For a distribution it returns the symbolic standard deviation. The variance of a normal distribution is sigma^2, so the standard deviation simplifies to sigma (distribution parameters are positive).

$ wo 'StandardDeviation[NormalDistribution[mu, sigma]]'
sigma

$ wo 'StandardDeviation[PoissonDistribution[lambda]]'
Sqrt[lambda]

The exactness follows the values: a Rational keeps the result symbolic, a machine number makes it a machine number.

$ wo 'StandardDeviation[{1/2, 3/2}]'
1/Sqrt[2]

$ wo 'StandardDeviation[{1., 3.}]'
1.4142135623730951