.. _method-multilevel_function_train-arithmetic_tolerance:

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arithmetic_tolerance
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A secondary rounding tolerance used for post-processing


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**Specification**

- *Alias:* None

- *Arguments:* REAL

- *Default:* 1.e-10


**Description**


After forming one or more function train approximations, this
tolerance is used for rolling up final results, in particular,
combining multilevel/multifidelity expansions and forming products for
higher-order moment estimation.  It is generally intended as a looser
tolerance than ``rounding_tolerance``.

*Default Behavior*

If this tolerance is not specified, then we adopt the internal C3 default.