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
.