The expectation value of a function in a variable
is denoted
or
. For a single discrete variable, it is defined by
(1)
|
where
is the probability density function.
For a single continuous variable it is defined by,
(2)
|
The expectation value satisfies
(3)
| |||
(4)
| |||
(5)
|
For multiple discrete variables
(6)
|
For multiple continuous variables
(7)
|
The (multiple) expectation value satisfies
(8)
| |||
(9)
| |||
(10)
|
where
is the mean for the variable
.