SPARQL中的幂(幂)和其他数学函数支持 [英] Power (exponentiation) and other math function support in SPARQL

问题描述

我正在尝试编写一个SPARQL查询，该查询要在某个对象的平方上进行过滤，但是我根本无法弄清楚如何对一个数字进行平方( x ² )(当然，除了将其与自身相乘).我猜想一个叫math:sqrt()的平方根函数可以工作，但似乎没有像math:pow这样的东西存在.

I am trying to write a SPARQL query where I want to filter on the square of something, but I am simply unable to figure out how to square a number (x²) (except by multiplying it with itself, of course). I guessed a square root function called math:sqrt() which works, yet nothing like math:pow seems to exist.

如何在SPARQL中求某物的平方，更重要的是，在哪里可以读到它以及SPARQL中的其他数学函数(例如math:sqrt)?

How do I get the square of something in SPARQL and, more importantly, where can I read about it and other math functions such as math:sqrt in SPARQL?

注意:这与我以前的问题有关:反向Wikipedia地理标记查询.

Note: This is related to my previous question: Reverse wikipedia geotagging lookup .

推荐答案

现在已经过了几年，并且

It's now a few years later and the SPARQL 1.1 Query Language has been published. It includes many more built-in functions than the original SPARQL query language. In addition to lots of functions on strings, RDF terms, &c., there are a number of numeric functions (the section numbers indicate the section in the linked standard):

• 17.4.4 数字功能
  • 17.4.4.1 abs
  • 17.4.4.2 回合
  • 17.4.4.3 ceil
  • 17.4.4.4 地板
  • 17.4.4.5 RAND

• 17.4.4 Functions on Numerics
  • 17.4.4.1 abs
  • 17.4.4.2 round
  • 17.4.4.3 ceil
  • 17.4.4.4 floor
  • 17.4.4.5 RAND

这里仍然没有square功能，最快的实现方式将使用*，因此 laalto的答案仍然站立. SPARQL支持的运算符在 17.3运算符映射和XPath中进行了描述.算术仍然只是+，-，*和/的集合.

There's still no square function here, and the quickest way to implement that will be using *, so laalto's answer still stands. The operators that SPARQL supports are described in 17.3 Operator Mapping, and for XPath arithmetic is still just the set of +, -, *, and /.

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