19c19
<             <xsl:if test="prime:test($N)!=''">
---
>             <xsl:if test="prime:test($N)">
35c35
<   <xsl:function name="prime:test" as="xs:string">
---
>   <xsl:function name="prime:test" as="xs:boolean">
38c38
<     <xsl:value-of select="if (($N > 2) and ($N mod 2)) then prime:testR($N,3) else ''"/>
---
>     <xsl:value-of select="if (($N > 2) and ($N mod 2)) then prime:testR($N,3) else false()"/>
41c41
<   <xsl:function name="prime:testR" as="xs:string*">
---
>   <xsl:function name="prime:testR" as="xs:boolean">
46,47c46,47
<       <xsl:when test="$t * $t > $N"><xsl:value-of select="'1'"/></xsl:when>
<       <xsl:when test="($N mod $t) = 0"/>
---
>       <xsl:when test="$t * $t > $N"><xsl:value-of select="true()"/></xsl:when>
>       <xsl:when test="($N mod $t) = 0"><xsl:value-of select="false()"/></xsl:when>