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».


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.

See Also


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