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[[Category:XQuery]]
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This [[Module Library|XQuery Module]] contains functions for computing random values. All functions except for {{CodeFunction||random:seeded-double}} and {{CodeFunction||random:seeded-integer}} are non-deterministicnondeterministic, i. e., they return different values for each call.
=Conventions=
All functions and errors in this module are assigned to the {{Code|<code><nowiki>http://basex.org/modules/random}} </nowiki></code> namespace, which is statically bound to the {{Code|random}} prefix.<br/>All errors are assigned to the {{Code|http://basex.org/errors}} namespace, which is statically bound to the {{Code|bxerr}} prefix.
=Functions=
==random:double==
{| width='100%'
|-valign="top"| width='120' | '''SignaturesSignature'''|{{Func|<pre>random:double||() as xs:double}}<br /pre>|-valign="top"
| '''Summary'''
|Returns a double value between 0.0 (inclusive) and 1.0 (exclusive).<br />|-| |
|}
==random:integer==
{| width='100%'
|-valign="top"| width='120' | '''SignaturesSignature'''|{{Func|random:integer||xs:integer}}<br /pre>{{Func|random:integer|( $max as xs:integer| := ()) as xs:integer}}<br /pre>|-valign="top"
| '''Summary'''
|Returns an integer value, either in the whole integer range or between 0 (inclusive) and the given maximum (exclusive)<br />|-valign="top"| '''Errors'''|{{Error|bounds|#Errors}} the maximum value is out of bounds.
|}
==random:seeded-double==
{| width='100%'
|-valign="top"| width='120' | '''SignaturesSignature'''|{{Func|<pre>random:seeded-double|( $seed as xs:integer, $num as xs:integer|) as xs:double*}}<br /pre>|-valign="top"
| '''Summary'''
|Returns a sequence with {{Code|$num}} double values between 0.0 (inclusive) and 1.0 (exclusive). The random values are created using the initial seed given in {{Code|$seed}}.<br />|-| |
|}
==random:seeded-integer==
{| width='100%'
|-valign="top"| width='120' | '''SignaturesSignature'''|{{Func|random:seeded-integer|$seed as xs:integer, $num as xs:integer|xs:integer*}}<br /pre>{{Func|random:seeded-integer|( $seed as xs:integer, $num as xs:integer, $max as xs:integer| := ()) as xs:integer*}}</pre>|-valign="top"
| '''Summary'''
|Returns a sequence with {{Code|$num}} integer values, either in the whole integer range or between 0 (inclusive) and the given maximum (exclusive). The random values are created using the initial seed given in {{Code|$seed}}.<br />|-valign="top"| '''Errors'''|{{Error|bounds|#Errors}} the maximum value is out of bounds.<br/>{{Error|negative|#Errors}} the number of values to be returned is negative.
|}
==random:gaussian==
{| width='100%'
|- valign="top"
| width='120' | '''Signature'''
|<pre>random:gaussian(
$num as xs:integer
) as xs:double*</pre>
|- valign="top"
| '''Summary'''
|Returns a sequence with {{Code|$num}} double values. The random values are Gaussian (i.e. normally) distributed with the mean 0.0. and the derivation 1.0.<br/>
|}
==random:seeded-permutation==
{| width='100%'
|-valign="top"| width='120' | '''SignaturesSignature'''|{{Func|<pre>random:gaussian|seeded-permutation( $num seed as xs:integer|xs:double, $items as item()*) as item()*}}<br /pre>|-valign="top"
| '''Summary'''
|Returns a sequence with random permutation of the specified {{Code|$numitems}} double values. The random values are Gaussian (i.e. normally) distributed with order is created using the mean 0.0. and the derivation 1.0initial seed given in {{Code|$seed}}.<br />|-| |
|}
==random:uuid==
{| width='100%'
|-valign="top"| width='120' | '''SignaturesSignature'''|{{Func|<pre>random:uuid||() as xs:string}}</pre>|-valign="top"
| '''Summary'''
|Creates a random universally unique identifier (UUID), represented as 128-bit value.
|-valign="top"
| '''Examples'''
|
* {{Code|random:uuid() eq random:uuid()}} will (most probably) return the boolean value {{Code|false}}.
|}
=Errors=
{| class="wikitable" width="100%"
! width="110"|Code
|Description
|- valign="top"
|{{Code|bounds}}
|The specified maximum value is out of bounds.
|- valign="top"
|{{Code|negative}}
|The specified number of values to be returned is negative.
|}
=Changelog=
;Version 9.0
* Updated: error codes updated; errors now use the module namespace
;Version 8.5
* Added: {{Function||random:seeded-permutation}}
;Version 8.0
* Updated: {{Function||random:integer}}, {{Function||random:seeded-integer}} raise error for invalid input.
The module was introduced with Version 7.5. It includes some functionality which was previously located in the [[Math_Module|Math Module]].
