XSL - 带xml的数学

Question

我想知道如何使用XSL在XML中显示以下内容？

displaying this formula:
(value1 * 5 + value2 * 4 + value3 * 3 + value4 * 2 + value5 * 1 / value1 + value2 + value3 + value4 + value5)

这里是从中获取值的地方：

<ratings>
<book>
    <title>Doctor Sleep</title>
    <author>Stephen King</author>
    <userRatings outOf="5">
        <numUsers vote="5">13411</numUsers> <!-- The number of users who voted 5 out of 5 -->
        <numUsers vote="4">14794</numUsers> <!-- The number of users who voted 4 out of 5 -->
        <numUsers vote="3">5359</numUsers> <!-- etc. -->
        <numUsers vote="2">974</numUsers>
        <numUsers vote="1">361</numUsers>
        <!-- total = 34899 -->
    </userRatings>
</book>
<book>
    <title>Gone Girl</title>
    <author>Gillian Flynn</author>
    <userRatings outOf="5">
        <numUsers vote="5">95595</numUsers>
        <numUsers vote="4">140217</numUsers>
        <numUsers vote="3">61642</numUsers>
        <numUsers vote="2">16923</numUsers>
        <numUsers vote="1">6225</numUsers>
        <!-- total = 320602 -->
    </userRatings>
</book>
</ratings>

这是我到目前为止所做的：

<average>
    <xsl:for-each select="document('ratings.xml')/ratings/book[title = $compareTitles]">
        <xsl:value-of select="sum(userRatings/numUsers * userRatings/numUsers/@vote) div sum(userRatings/numUsers)"/>
    </xsl:for-each>
</average>

我尝试使用变量，但发现你不能操纵一个已定义的变量，并且在声明时它是固定的。

修改

<average>
    <xsl:for-each select="document('ratings.xml')/ratings/book[title = $compareTitles]">
        <xsl:value-of select="format-number(((userRatings/numUsers[@vote = '1'] * 1) +
                                 (userRatings/numUsers[@vote = '2'] * 2) +
                                 (userRatings/numUsers[@vote = '3'] * 3) +
                                 (userRatings/numUsers[@vote = '4'] * 4) +
                                 (userRatings/numUsers[@vote = '5'] * 5))
                                 div (userRatings/numUsers[@vote = '5'] +
                                 userRatings/numUsers[@vote = '4'] +
                                 userRatings/numUsers[@vote = '3'] +
                                 userRatings/numUsers[@vote = '2'] +
                                 userRatings/numUsers[@vote = '1']),'0.##')"/>
    </xsl:for-each>
</average>