Just a note of caution. Yourdon's techniques have been around since at least the 70's. They are tried and proven. I used them for 15 years. They are just another way of looking at and presenting requirements, functions, etc.
Unfortunately for Yourdon, the industry has moved away from his data driven approach to the behavioural approach espoused in the UML. Yourdon is to Analysis as Cobol is to programming.
Kimbo