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Appendix D

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This section is devoted to the recursive template used to create a sequence of partial sums of a sequence of integers. The code for this template is shown in Figure 24.


makeURPs.xsl Recursive Template - Figure 24

 

[F24H0] The valsargument should contain a sequence of integers. In recursive calls, vals refers to the tail subsequence formed by dropping the first term.

[F24H1] The seq argument should start as the empty sequence (). In recursive calls, seq will refer to the sequence of partial sums.

[F24H2] The nxtval argument starts with an initial value of 0 and so need not be present in the first call. In recursive calls it refers to the sum of its last value and the first term in the vals sequence.

[F24H3] This test allows the recursion to continue while there are terms left in the sequence vals (see [F24H5]).

[F24H4] This is the recursive call where

  • [F24H4a] The XPATH expression is the tail of the vals sequence with the first term dropped.
  • [F24H4b] This parameter uses the sequence constructor () to add the value of  nxtval to the end of the sequence seq.
  • [F24H4c] The new value of nxtval is the old value plus the first term of the  vals sequence.

[F24H5] This declares the sequence seq as the result when vals is exhausted (see [F24H3]).

 

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