.. _method-multilevel_polynomial_chaos-variance_based_decomp-interaction_order:

"""""""""""""""""
interaction_order
"""""""""""""""""


Specify the maximum number of variables allowed in an interaction when reporting interaction metrics.


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**Specification**

- *Alias:* None

- *Arguments:* INTEGER

- *Default:* Unrestricted (VBD includes all interaction orders present in the expansion)


**Description**


The interaction_order option has been added to allow suppression of higher-order interactions, since the output volume (and memory and compute consumption) of these results could be extensive for high dimensional problems (note: the previous univariate_effects specification is equivalent to interaction_order = 1 in the current specification). Similar to suppression of interactions is the covariance control, which can be selected to be diagonal_covariance or full_covariance, with the former supporting suppression of the off-diagonal covariance terms (to again save compute and memory resources and reduce output volume)


