Dakota Reference Manual: loguniform_uncertain

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loguniform_uncertain

Aleatory uncertain variable - loguniform

## Topics

This keyword is related to the topics:

- continuous_variables
- aleatory_uncertain_variables

## Specification

Alias: none

Argument(s): INTEGER

Default: no loguniform uncertain variables

Child Keywords:

| Required/Optional | Description of Group | Dakota Keyword | Dakota Keyword Description
--- | --- | --- | --- | ---
| Required | lower_bounds | Specify minimum values
| Required | upper_bounds | Specify maximium values
| Optional | initial_point | Initial values for variables
| Optional | descriptors | Labels for the variables

## Description

If the logarithm of an uncertain variable X has a uniform distribution, that is then X is distributed with a loguniform distribution. The distribution lower bound is and upper bound is The loguniform distribution has the density function:

## Theory

For some methods, including vector and centered parameter studies, an initial point is needed for the uncertain variables. When not given explicitly, these variables are initialized to their means.