Poisson Command

Poisson( <Mean> )

Returns a bar graph of a Poisson distribution with given mean λ.

Poisson( <Mean>, <Boolean Cumulative> )

Returns a bar graph of a Poisson distribution when Cumulative = false.

Returns a graph of a cumulative Poisson distribution when Cumulative = true.

The first parameter is same as above.

Poisson( <Mean>, <Variable Value v>, <Boolean Cumulative> )

Let X be a Poisson random variable.

Returns P( X = v) when Cumulative = false.

Returns P( X ≤ v) when Cumulative = true.

First parameter is same as above.

Examples:

• Poisson(3, 1, true) yields 0.2 in the Algebra View and \frac{4}{e³} in the CAS View.
• Poisson(3, 1, false) yields 0.15 in the Algebra View and \frac{3}{e³} in the CAS View.

Note: A simplified syntax is available to calculate P(u ≤ X ≤ v): e.g. Poisson(1, 1..5) yields 0.63153, that is the same as Poisson(1, {1, 2, 3, 4, 5}).