Probability mass function
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In probability theory, a probability mass function (p(x)) is a real-valued function of a discrete variable (x), such that the value p(xk) is the probability of the variable x having the value xk.
In order to qualify, such a function must meet the following criteria:
- <math>p(x_{k}) \geq 0; \forall x </math>
- <math>\sum_{k} p(x_{k}) = 1 </math>
The collection of pairs ( xk , p(xk) ) is the discrete probability distribution of x.