title: subset of array C of set length
body: <p>Suppose I have a double array <code>double myArray[16]</code> with 16 elements. I want to perform a function on each subset of four elements, i.e. the first subset is <code>myArray[0], myArray[1], myArray[2], myArray[3]</code>, the second is <code>myArray[4], myArray[5], myArray[6], myArray[7]</code>, and so on. </p>
  
  <p>I want to pass the subset arrays using a pointer to a <code>void</code> function that operates on the subset only and write the values to the addresses passed to the function. If I wanted to use all the elements beginning with <code>myArray[8]</code>, I could pass <code>&amp;myArray[8]</code> to the function, but I need to pass only a predetermined length (4 in this example). </p>
  
  <p>Any help is appreciated!</p>