Returns its operand with the sign reversed: (- $arg).
op:numeric-unary-minus( $arg as xs:numericxs:numericGeneral rules: see .
The returned value is an instance of xs:integer, xs:decimal,
xs:double, or xs:float depending on the type of
$arg.
For xs:integer and xs:decimal arguments, 0 and
0.0 return 0 and 0.0, respectively. For
xs:float and xs:double arguments, NaN returns
NaN, 0.0E0 returns -0.0E0 and vice versa.
INF returns -INF. -INF returns
INF.