Blurb::
Do not scramble this digital net

Description::
The digital net should preserve the structure of the points after randomization. 
This can be achieved by *scrambling* the digital net. Scrambling can also improve the rate of convergence 
of a method that uses these scrambled points to compute the mean of the model response. 
Owen's scrambling :cite:p:`Owen98` is the most well-known scrambling technique. A particular variant 
is linear matrix scrambling, which is implemented in Dakota :cite:p:`Matouvsek98`.
In linear matrix scrambling, we left-multiply each generating matrix with a lower-triangular random scramble matrix. 
The number of rows in the scramble matrix can be set with the keyword :dakkw:`method-sampling-sample_type-low_discrepancy-digital_net-t_scramble`.

*Usage tips*

When this keyword is provided, the digital net points will not be scrambled. 
Unscrambled digital net points are generally less performant compared to their scrambled counterparts, so it is highly recommended to 
not use this keyword, unless you're absolutely sure you know what you're doing.

Topics::

Examples::

.. code-block::

    environment
      tabular_data
        tabular_data_file = 'samples.dat'
        freeform

    method
      sampling
        samples 32
        sample_type
          low_discrepancy
            digital_net
              generating_matrices inline 
                1 2 4 8 16
                # this encodes the generating matrix
                # 1 0 0 0 0
                # 0 1 0 0 0
                # 0 0 1 0 0 
                # 0 0 0 1 0
                # 0 0 0 0 1
                1 3 5 15 17
                # this encodes the generating matrix
                # 1 1 1 1 1
                # 0 1 0 1 0
                # 0 0 1 1 0
                # 0 0 0 1 0
                # 0 0 0 0 1
              m_max 5
              t_max 5
              no_scrambling
              no_digital_shift

    variables
      uniform_uncertain = 2
        lower_bounds 0.0 0.0
        upper_bounds 1.0 1.0

    interface
      analysis_drivers = 'genz'
      analysis_components = 'cp1'
      direct

    responses
      response_functions = 1
      no_gradients
      no_hessians

Theory::

Faq::

See_Also::
