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[Bug 29356] New: Add fn:product

From: <bugzilla@jessica.w3.org>
Date: Sun, 03 Jan 2016 21:30:29 +0000
To: public-qt-comments@w3.org
Message-ID: <bug-29356-523@http.www.w3.org/Bugs/Public/>
https://www.w3.org/Bugs/Public/show_bug.cgi?id=29356

            Bug ID: 29356
           Summary: Add fn:product
           Product: XPath / XQuery / XSLT
           Version: Working drafts
          Hardware: PC
                OS: Linux
            Status: NEW
          Severity: normal
          Priority: P2
         Component: Requirements for Future Versions
          Assignee: jim.melton@acm.org
          Reporter: benito@benibela.de
        QA Contact: public-qt-comments@w3.org
  Target Milestone: ---

There is a fn:sum, but no fn:product

That does not seem intuitive. Both are the basic commutative arithmetic
operations, there should either be both or neither.

It is also very useful to calculate the factorial: product(1 to $something)

>From that you can define the binomial (which could also be useful in the math:
module):

declare function binomial($n, $k) { product(($k + 1) to $n) div product(1 to (n
- k)) } 

and work with combinatorics and stuff

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Received on Sunday, 3 January 2016 21:30:32 UTC

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