=====adjacent_difference=====
Syntax:

<code>
    #include <numeric>
    output_iterator adjacent_difference( input_iterator start, input_iterator end, output_iterator result );
    output_iterator adjacent_difference( input_iterator start, input_iterator end, output_iterator result, BinaryFunction f );
</code>
The adjacent_difference() function calculates the differences between adjacent
elements in the range [start,end) and stores the result starting at result.
(Specifically, the element at start will be copied to result; and then the difference
between the element at start + i and start + (i-1) will be stored at result + i.)

If a binary function f is given, it is used instead of the - operator to
compute the differences.
adjacent_difference() runs in [[/complexity|linear time]].

Following example displays the differences between adjacent elements in a vector.
<code>
 #include <vector>
 #include <iostream>
 #include <iterator>
 #include <algorithm>
 #include <numeric>

 int main()
 {
   std::vector<int> v;
   for (int i = 1; i <= 10; ++i)
     v.push_back(i);

   // display elements of v
   std::copy(v.begin(), v.end(), std::ostream_iterator<int>(std::cout, " "));

   std::cout << std::endl

   // display all differences between elements
   std::adjacent_difference(v.begin(), v.end(), std::ostream_iterator<int>(std::cout, " "));

   return 0;
 }
</code>

When run, this code displays the following output: 
<code>
 1 2 3 4 5 6 7 8 9 10 
 1 1 1 1 1 1 1 1 1 1
</code>

Related Topics: [[accumulate]], [[count]], [[inner_product]], [[partial_sum]]