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Update mixture distribution

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update storeage of c++ class
  update sampling -> uses std::lower_bound for O(log(N)) sampling of the
distribution
  implemented from_xml_element
  updated settings.rst
  include a mixture in the regression tests
This commit is contained in:
Olaf Schumann 2021-09-23 09:34:11 +00:00
parent 1c219600a1
commit e7fa663b3d
7 changed files with 98 additions and 30 deletions
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18
docs/source/io_formats/settings.rst
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@ -619,16 +619,17 @@ variable and whose sub-elements/attributes are as follows:
:type:
The type of the distribution. Valid options are "uniform", "discrete",
"tabular", "maxwell", and "watt". The "uniform" option produces variates
sampled from a uniform distribution over a finite interval. The "discrete"
option produces random variates that can assume a finite number of values
(i.e., a distribution characterized by a probability mass function). The
"tabular" option produces random variates sampled from a tabulated
"tabular", "maxwell", "watt", and "mixture". The "uniform" option producess
variates sampled from a uniform distribution over a finite interval. The
"discrete" option produces random variates that can assume a finite number
of values (i.e., a distribution characterized by a probability mass function).
The "tabular" option produces random variates sampled from a tabulated
distribution where the density function is either a histogram or
linearly-interpolated between tabulated points. The "watt" option produces
random variates is sampled from a Watt fission spectrum (only used for
energies). The "maxwell" option produce variates sampled from a Maxwell
fission spectrum (only used for energies).
fission spectrum (only used for energies). The "mixture" option produces samples
from univariate sub-distributions with given probabilities.
*Default*: None
@ -649,6 +650,11 @@ variable and whose sub-elements/attributes are as follows:
number :math:`a` that parameterizes the distribution :math:`p(x) dx = c x
e^{-x/a} dx`.
For a "mixture" distribution, ``parameters`` provide the :math:'(p,d)' pairs
connecting the probabilites :math:'p' with the different sub-distributions
:math:'d'. All probabilities :math:'p' are given first followed by the corresponding
distributions :math:'d'.
.. note:: The above format should be used even when using the multi-group
:ref:`energy_mode`.
:interpolation: