# Manuals/calci/poisson

POISSON(x,m,cu)

• is the number of events.
• is the mean
• is the logical value like TRUE or FALSE.

## Description

• This function gives the value of the Poisson distribution.
• The Poisson distribution is a discrete probability distribution for the counts of events that occur randomly in a given interval of time.
• It is is used to model the number of events occurring within a given time interval.
• In , is the number of events in a given interval of time, is the Average Numeric value and is the logical value.
• If it is TRUE, this function will give the Cumulative Poisson Probability with the number of random events between and (included).
• If it is FALSE, this function will give the Poisson Probability Mass function with the number of events occurring will be exactly .
• The probability mass function is:

where is the shape parameter and . is the base of the natural logarithm (e=2.718282).

• The Cumulative Poisson Probability function is:

.

• This function will return the result as error when
1. or  is non-numeric.
2. or .


## Examples

1. =POISSON(6,2,TRUE) = 0.995466194
2. =POISSON(6,2,FALSE) = 0.012029803
3. =POISSON(10.2,7,TRUE) = 0.901479206
4. =POISSON(10.2,7,FALSE) = 0.070983269
5. =POISSON(6,0,TRUE) = 1

POISSON