Most agile teams use some upfront design, and most formal methods are iterative.
Vinekar, Vishnu and Huntley, Christopher, "Agility versus Maturity: Is There Really a Trade-Off?" (2010). Business Faculty Publications. 32.
Vinekar, Vishnu and Christopher L. Huntley. 2010. Agility versus Maturity: Is There Really a Trade-Off? IEEE Computer, 43 (5) 87-89.