Dakota Reference Manual  Version 6.4
Large-Scale Engineering Optimization and Uncertainty Analysis
 All Pages
list_parameter_study


Samples variables as a specified values

Topics

This keyword is related to the topics:

Specification

Alias: none

Argument(s): none

Required/Optional Description of Group Dakota Keyword Dakota Keyword Description
Required
(Choose One)
Group 1 list_of_points

List of variable values to evaluate in a list parameter study

import_points_file

File containing list of variable values to evaluate in a list parameter study

Optional model_pointer

Identifier for model block to be used by a method

Description

Dakota's list parameter study allows for evaluations at user selected points of interest.

Default Behavior

By default, the list parameter study operates over all types of variables.

The number of real values in the list_of_points specification or file referenced by import_points_file must be a multiple of the total number of variables (including continuous and discrete types) contained in the variables specification.

Expected Outputs

A list parameter study produces a set of responses for each parameter set that is specified.

Usage Tips

  • This parameter study simply performs simulations for the first parameter set (the first n entries in the list), followed by the next parameter set (the next n entries), and so on, until the list of points has been exhausted.
  • Since the initial values from the variables specification will not be used, they need not be specified.
  • When the points are specified in the Dakota input file using the list_of_points keyword, discrete set values must be referred to using 0-based indexes, and not the values themselves. However, when using import_points_file, refer to discrete set values directly, not by index.
  • For both list_of_points and import_points_file, Dakota expects the values for each evaluation to be ordered by type. The type ordering matches that of the variables section of this Reference Manual and of the listing in the Parameters file format section of the Dakota User's Manual[5]. When multiple variables are present for a single type, the ordering within that type must match the order specified by the user in the variables section of her input file.

Examples

This shows the method and variables block of a Dakota input file that runs a list_parameter_study.

method
  list_parameter_study
    list_of_points =
                 3.1e6    0.0029    0.31  
                 3.2e6    0.0028    0.32 
                 3.3e6    0.0027    0.34 
                 3.3e6    0.0026    0.36  

variables
  continuous_design = 3
    descriptors = 'E'    'MASS'     'DENSITY'

Note that because of the way Dakota treats whitespace, the above example is equivalent to:

method
  list_parameter_study
    list_of_points =
3.1e6    0.0029    0.31  3.2e6    0.0028    
0.32    3.3e6    0.0027    
0.34  3.3e6    0.0026    0.36

variables
  continuous_design = 3
    descriptors = 'E'  'MASS'   'DENSITY'

Although the first example is much more readable.

And here's a full input file:

# tested on Dakota 6.0 on 140501
environment
  tabular_data
    tabular_data_file 'List_param_study.dat'

method
  list_parameter_study
    list_of_points =     0.1    0.1
                         0.2    0.1
                         0.3    0.0
                         0.3    1.0

model
  single

variables
  active design
  continuous_design = 2
    descriptors    'x1' 'x2'
  continuous_state = 1
    descriptors =   'constant1'
    initial_state = 100

interface
  analysis_drivers 'text_book'
    fork
  asynchronous
    evaluation_concurrency 2

responses
  response_functions = 1
  no_gradients
  no_hessians

This example illustrates the list_parameter_study.

  • The function evaluations are independent, so any level of evaluation_concurrency can be used
  • Default behavior for parameter studies is to iterate on all variables. However, because active design is specified, this study will only iterate on the continuous_design variables.

See Also

These keywords may also be of interest: