This problem is about processing structure arrays. Write a function named structSort that sorts a structure array based on a given field that contains numerical values. Your function should take in a structure array and a string that should correspond to one of the fields of the structure array and return the original structure array sorted on the given field. It should check to be sure that the specified field name is in fact one of the fields of the structure array, and call the error(...) function if it is not.
Test your function by using the buildCDs script from Chapter 7, using the input function to specify the sorting field.