Exponential

Function for generating values from exponential distributions

Interface

exponential(r:real) : real

where r>0.0. Gives a drawing from a exponential distribution with intensity r.

Raises Exponential exception, if r⇐0.0.

Characteristics

Mean: 1/r
Variance: 1/r^2

Density functions for exponential distributions:

Density functions for exponential distributions

Example

exponential(1.0/4.0)

Customers arrive at a post office for service. The time between two arrivals has a mean of 4 minutes. The inter-arrival time has a exponential distribution with parameter r=1/4.

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