Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. In mathematics, the Dirichlet (or first-type) boundary condition is a type of boundary condition, named after Johann Peter Gustav Lejeune Dirichlet (1805-1859). When imposed on an ordinary or a partial differential equation, it specifies the values a solution needs to take on the boundary of the domain. The question of finding solutions to such equations is known as the Dirichlet problem.Dirichlet boundary conditions are perhaps the easiest to understand but there are many other conditions possible. For example, there is the Cauchy boundary condition or the mixed boundary condition which is a combination of the Dirichlet and Neumann conditions.