Rounds a value to a specified number of decimal places, rounding upwards if two such values are equally near.
fn:round
( $arg
as xs:numeric?
xs:numeric?
fn:round
( $arg
as xs:numeric?
,$precision
as xs:integer
xs:numeric?
General rules: see .
The function returns the nearest (that is, numerically closest) value to
$arg
that is a multiple of ten to the power of minus
$precision
. If two such values are equally near (for example, if the
fractional part in $arg
is exactly .5), the function returns the one that
is closest to positive infinity.
For the four types xs:float
,
xs:double
, xs:decimal
and xs:integer
, it is
guaranteed that if the type of $arg
is an instance of type T then
the result will also be an instance of T. The result may
also be an instance of a type derived from one of these four by restriction. For example, if
$arg
is an instance of xs:decimal
and $precision
is less than one,
then the result may
be an instance of xs:integer
.
The single-argument version of this function produces the same result as the
two-argument version with $precision=0
(that is, it rounds to a whole
number).
When $arg
is of type xs:float
and xs:double
:
If $arg
is NaN, positive or negative zero, or positive or negative
infinity, then the result is the same as the argument.
For other values, the argument is cast to xs:decimal
using an
implementation of xs:decimal
that imposes no limits on the number of
digits that can be represented. The function is applied to this
xs:decimal
value, and the resulting xs:decimal
is
cast back to xs:float
or xs:double
as appropriate to
form the function result. If the resulting xs:decimal
value is zero,
then positive or negative zero is returned according to the sign of
$arg
.
The expression fn:round(2.5)
returns 3.0
.
The expression fn:round(2.4999)
returns 2.0
.
The expression fn:round(-2.5)
returns -2.0
.
The expression fn:round(1.125, 2)
returns 1.13
.
The expression fn:round(8452, -2)
returns 8500
.
The expression fn:round(3.1415e0, 2)
returns 3.14e0
.
This function is typically used with a non-zero $precision
in financial
applications where the argument is of type xs:decimal
. For arguments of
type xs:float
and xs:double
the results may be
counter-intuitive. For example, consider round(35.425e0, 2)
. The result is
not 35.43, as might be expected, but 35.42. This is because the xs:double
written as 35.425e0 has an exact value equal to 35.42499999999..., which is closer to
35.42 than to 35.43.