is not regarded as having a direct role in fluid mechanics but is included because he is my son's favorite mathematician. was the first to represent mathematical quantities by letters and introduced the plus (+) and minus (-) symbols. He derived a formula for p in the form of an infinite product. His substitution method for the solution of polynomials still goes by his name. Finally, he was the first to describe the law of cosines and developed multiple angle formulas. The latter were used in his famous product for 2/ p . Viète trai ....