Define how Dakota should run a function evaluation


  • Alias: None

  • Arguments: STRINGLIST

Child Keywords:


Description of Group

Dakota Keyword

Dakota Keyword Description



Run a pre-processing script before the analysis drivers



Run a post-processing script after the analysis drivers

Required (Choose One)

Interface Type


(Not recommended) Launch analysis drivers with a system call


Launch analysis drivers using fork command


Run analysis drivers that are linked-to or compiled-with Dakota


Dynamically load a plugin analysis driver


Run Matlab through a direct interface - requires special Dakota build


Run Python through a Pybind11-based direct interface - requires a special Dakota build


Run Python through a deprecated C-based direct interface - requires a special Dakota build


Run Scilab through a direct interface - requires special Dakota build


Deprecated grid computing interface



Provide additional identifiers to analysis drivers.


The analysis_drivers keyword provides the names of one or more executable analysis programs or scripts, a.k.a. “drivers” which comprise a function evaluation. The optional and required sub-keywords specify how Dakota will manage directories and files, and run the driver(s).

Types of Interfaces

Dakota has two recommended ways of running analysis drivers:

  • as an external processes ( fork), or

  • using internal code to couple to the analysis driver ( direct)

Other options are available for advanced users, and are not as well documented, supported, or tested:

  • external processes ( system)

  • internal coupling ( python, matlab, scilab, grid)

Use Cases

The internally coupled codes have few options because many of the details are already handled with the coupling. Their behavior is described in the direct keyword.

For external processes using the fork keyword,

A function evaluation may comprise:

  • A single analysis driver: Function evaluation, including all pre- and post-processing is contained entirely within a single script/executable.

  • A single analysis driver with filters: Function evaluation is explicitly split into pre-processing (performed by the input filter), analysis, and post-processing (by the output filter).

  • A single analysis driver with environment variables: Function evaluation is contained within one analysis driver, but it requires environment variables to be set before running.

  • Multiple analysis drivers: Drivers are run sequentially or concurrently (See the asynchronous keyword) and can have any of the above options as well.

For fork and system interfaces, the analysis_driver list contains the names of one or more executable programs or scripts taking parameters files as input and producing results files as output. The first field in each analysis driver string must be an executable program or script for Dakota to spawn to perform the function evaluation. Drivers support:

  • One set of nested quotes, for arguments with spaces

  • Dakota will define special environment variables DAKOTA_PARAMETERS_FILE and DAKOTA_RESULTS_FILE which can be used in the driver script.

  • Dakota will replace the tokens {PARAMETERS} and {RESULTS} in an anslysis driver string with the names of the parameters and results files for that analysis/evaluation. Along with the verbatim keyword, which prevents Dakota from appending the names of the parameters and reslts files as command line arguments, this feature provides users with greater control over how their analysis drivers are invoked by Dakota.

  • Variable definitions preceding the executable program or script, such as ‘MY_VAR=2’ are no longer supported.

For details and examples see the Simulation Interface Components section of the Interfaces chapter of the User’s Manual; for details on the filters and environment variables, see the subsection on Syntax for Filter and Driver Strings.



1. analysis_drivers = '' ''

2. analysis_driver = ' -option "option 1"'

3. analysis_driver = 'simulation.exe -option value -dakota_params $DAKOTA_PARAMETERS_FILE -input -dakota_results_file $DAKOTA_RESULTS_FILE'


Where will Dakota look for the analysis_driver? Dakota will locate analysis_driver programs first in (or relative to) the present working directory (“.”, the interface-analysis_drivers-fork-work_directory if used, otherwise the directory in which Dakota is started), then the directory from which Dakota is started, then using the system $PATH environment variable (Path% on Windows).

Where should the driver be located? When the driver is a script it is most commonly placed in the same directory as the Dakota input file. When using a work_directory, Dakota will also look for drivers in the specified working directory, so link_files or copy_files may specify the driver to get copied or linked into the work directory. When executable programs are used as drivers, they are often elsewhere on the filesystem. These can be specified using absolute paths, or by prepending the PATH environment variable so Dakota finds them.

What if Dakota fails to run my analysis_driver? Prepend the absolute location of the driver to the PATH environment variable before running Dakota, or specify an absolute path to the driver in the Dakota input file.