The ApplyRule( expr, rule ) command applies the specified rounding rule rule to all Quantity objects in expr.

If the optional parameter rule is given, rule is used to perform any rounding operations.  Otherwise, the default rounding rule is used ('digits', or as set by UseRule).

The rule may require an index.

All Quantity objects are replaced by new Quantity objects with a central value and absolute uncertainty rounded according to the specified rule.

In the case of the rule 'digits', no rounding is performed.

A Quantity object is rounded by passing its central value and absolute uncertainty to a procedure that performs the action of the particular rule. The procedure returns the new central value and absolute uncertainty, which ApplyRule places in a new Quantity(...) object.

For more information on predefined rules in ScientificErrorAnalysis, see Predefined Rounding Rules.

$\mathrm{with}\left(\mathrm{ScientificErrorAnalysis}\right)\:$

$\mathrm{e1}≔\mathrm{Quantity}\left(1.2088\,0.563\right)$

$\mathrm{e1}≔\mathrm{Quantity}\left(1.2088\,0.563\right)$

$\mathrm{ApplyRule}\left(\mathrm{e1}\,\mathrm{round}\left[2\right]\right)$

$\mathrm{Quantity}\left(1.21\,0.56\right)$