Pre-requisite: 64628/64622+64624+basic probability theory such as 64621/64636
This unit is broadly divided into three strands. Calculus of variations introduces the finding of optimal functions and reaffirms the close connection between boundary conditions and DEs. Stochastic differential equations reflect volatilty in finance and occur in other areas. The unit establishes a basic mathematical foundation for SDEs, shows some analytic solutions, and develops simple numerical schemes for simulation. Cryptography is important in maintaining electronic privacy. This unit applies number theory to commonly used cryptosystems.