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                       Standard C++ Library
             Copyright 1998, Rogue Wave Software, Inc.


NAME
     adjacent_difference

      - Outputs a sequence of the differences between each  adja-
     cent pair of elements in a range.



SYNOPSIS
     #include <numeric>
     template <class InputIterator, class OutputIterator>
     OutputIterator adjacent_difference (InputIterator first,
                                        InputIterator last,
                                        OutputIterator result);
     template <class InputIterator,
              class OutputIterator,
              class BinaryOperation>
     OutputIterator adjacent_difference (InputIterator first,
                                        InputIterator last,
                                        OutputIterator result,
                                        BinaryOperation bin_op);



DESCRIPTION
     Informally, adjacent_difference fills a  sequence  with  the
     differences  between successive elements in a container. The
     result is a sequence in which the first element is equal  to
     the  first  element of the sequence being processed, and the
     remaining elements are equal to the  calculated  differences
     between    adjacent   elements.   For   instance,   applying
     adjacent_difference  to  {1,2,3,5}  produces  a  result   of
     {1,1,1,2}.

     By default, subtraction is used to compute  the  difference,
     but  you can supply any binary operator. The binary operator
     is then applied to adjacent elements. For example,  by  sup-
     plying  the  plus  (+)  operator,  the  result  of  applying
     adjacent_difference to {1,2,3,5} is the sequence {1,3,5,8}.

     Formally,_adjacent_difference  assigns  to   every   element
     referred to by iterator i in the range [result + 1, result +
     (last - first)) a value equal to the appropriate one of  the
     following:

     *(first + (i - result)) - *(first + (i - result) - 1)
     or


     binary_op (*(first + (i - result)),
                *(first + (i - result) - 1))

     result is assigned the value of *first.

     binary_op should not have side effects.

     adjacent_difference returns result + (last - first).

     result can be equal to first. This allows you to  place  the
     results  of  applying  adjacent_difference into the original
     sequence.



COMPLEXITY
     This algorithm performs exactly (last-first)  -  1  applica-
     tions of the default operation (-) or binary_op.



EXAMPLE
     //
     // adj_diff.cpp
     //
      #include<numeric>       //For adjacent_difference
      #include<vector>        //For vector
      #include<functional>    //For times
      #include <iostream>
     using namespace std;
     int main()
      {
        //
        //Initialize a vector of ints from an array
        //
       int arr[10] = {1,1,2,3,5,8,13,21,34,55};
       vector<int> v(arr,arr+10);
        //
        //Two uninitialized vectors for storing results
        //
       vector<int> diffs(10), prods(10);
        //
        //Calculate difference(s) using default operator (minus)
        //
       adjacent_difference(v.begin(),v.end(),diffs.begin());
        //
        //Calculate difference(s) using the times operator
        //
       adjacent_difference(v.begin(), v.end(), prods.begin(),
             times<int>());
        //
        //Output the results
        //
       cout << "For the vector: " << endl << "     ";
       copy(v.begin(),v.end(),
            ostream_iterator<int,char>(cout," "));
       cout << endl << endl;
       cout << "The differences between adjacent elements are: "
             << endl << "     ";
       copy(diffs.begin(),diffs.end(),
            ostream_iterator<int,char>(cout," "));
       cout << endl << endl;
       cout << "The products of adjacent elements are: "
             << endl << "     ";
       copy(prods.begin(),prods.end(),
            ostream_iterator<int,char>(cout," "));
       cout << endl;
       return 0;

     Program Output



     For the vector:
         1 1 2 3 5 8 13 21 34 55
     The differences between adjacent elements are:
        1 0 1 1 2 3 5 8 13 21
     The products of adjacent elements are:
         1 1 2 6 15 40 104 273 714 1870



WARNINGS
     If your compiler does not support default  template  parame-
     ters,  then you always need to supply the Allocator template
     argument. For instance, you have to write:


     vector<int,allocator<int> >

     instead of:


     vector<int>

     If your compiler does not support namespaces,  then  you  do
     not need the using declaration for std.

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