# Mid

## Mid(x)

Evaluates «x» in Mid-Mode, i.e. deterministically.

Whenever an expression or subexpression is evaluated, it is evaluated either in *Mid-mode* or *Sample-mode*, in which sample-mode carries through information about uncertainty whereas mid-mode does not. The article on Evaluation Modes explains this in detail. **Mid**(x) forces the evaluation of «x» to occur in Mid-mode even when the current evaluation mode is sample-mode.

The Sample function does the opposite -- forcing «x» to be evaluated in sample mode.

Distribution functions return their median value in Mid-mode, or a Monte Carlo when evaluated in Sample-mode.

**Mid** is also used as an *meta-expression* in a MultiTable to show the computed value of «x».

## Examples

Suppose `x := Uniform(-1, 1)^2`

`Mid(x) → 0`

`Median(x) → 0.25`

`Mean(x) → 0.3333`

When **Mid** is evaluated, the median value of `Uniform(-1, 1)`

is used, which is 0 and is then squared to get the mid-value of `x`

. As seen, this is not equivalent to the median of `x`

when uncertainty is properly accounted for.

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