EXPONDIST Function

Basic Description

The Excel Expondist function returns the value of the exponential distribution for a give value of x. The user can specify whether the probability density function or the cumulative distribution function is used.

Syntax: EXPONDIST( x, lambda, cumulative )

Where the function arguments are:

x The value at which the exponential distribution is to be evaluated (must be ≥ 0)
lambda The parameter of the distribution
cumulative A logical argument that specifies the type of distribution to be calculated. This can be either:

TRUE calculate the cumulative distribution function
FALSE calculate the probability density function


Expondist Function Examples

Example 1 – Probability Density Function

The chart on the right shows the Exponential Distribution probability density function with the parameter λ set to 0.5, 1, and 2.

If you want to calculate the value of the probability density function with the parameter λ set to 1, at the value x = 0.5, this can be done, using the Excel Expondist function, as follows:

=EXPONDIST( 0.5, 1, FALSE )

This gives the result 0.60653066.

Plot of the Exponential Distribution Probability Density Function with the Parameter lambda set to 0.5, 1 and 2

Probability Density Exponential Distribution with λ = 0.5, 1 and 2
Example 2 – Cumulative Distribution Function

The chart on the right shows the Cumulative Exponential Distribution Functions with the parameter λ set to 0.5, 1 and 2.

If you want to calculate the value of the cumulative function with the parameter λ set to 1, at the value x = 0.5, this can be done using the Excel Expondist function, as follows:

=EXPONDIST( 0.5, 1, TRUE )

This gives the result 0.39346934.

Plot of the Cumulative Exponential Distribution with the Parameter lambda set to 0.5, 1 and 2

Cumulative Exponential Distribution with λ = 0.5, 1 and 2

 

Expondist Function Errors

If you get an error from the Excel Expondist function this is likely to be one of the following :

#NUM! Occurs if either the supplied value of x is negative or the supplied lambda argument is ≤ 0
#VALUE! Occurs if any of the supplied arguments are not recognised as numeric values

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