# Re: Using divide-and-conquer recursion to create a cu

 Subject: Re: Using divide-and-conquer recursion to create a cumulative sequence From: Andrew Welch Date: Sat, 12 Dec 2009 10:11:01 +0000
```2009/12/11 Costello, Roger L. <costello@xxxxxxxxx>:
>
> Hi Folks,
>
> I wish to convert a sequence of N numbers:
>
>   (23, 41, 70, 103, 99, 6)
>
> Into a cumulative sequence, in which each number is the sum of the previous
numbers:
>
>   (23, 64, 134, 237, 336, 342)

Hi Roger,

Here's a function that recursively processes sequence, with linear
performance:

<xsl:stylesheet version="2.0"
xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
xmlns:xs="http://www.w3.org/2001/XMLSchema"
xmlns:f="f"
exclude-result-prefixes="xs">

<xsl:variable name="seq" select="(23, 41, 70, 103, 99, 6)" as="xs:integer+"/>

<xsl:function name="f:sumSeq" as="xs:integer+">
<xsl:param name="seq" as="xs:integer+"/>
<xsl:param name="pos" as="xs:integer"/>

<xsl:sequence select="if (\$pos gt count(\$seq)) then \$seq else
f:sumSeq((subsequence(\$seq, 1, \$pos), \$seq[\$pos + 1] + \$seq[\$pos],
subsequence(\$seq, \$pos + 2)), \$pos + 1)"/>
</xsl:function>

<xsl:template match="/">
<xsl:value-of select="f:sumSeq(\$seq, 1)"/>
</xsl:template>

</xsl:stylesheet>

cheers
--
Andrew Welch
http://andrewjwelch.com
Kernow: http://kernowforsaxon.sf.net/

```

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