In mathematics, an equation that contains
It can be read as a statement about how a process evolves without specifying the formula defining the process. Given the initial state of the process (such as its size at time zero) and a description of how it is changing (i.e., the partial differential equation), its defining formula can be found by various methods, most based on {{link=integration">integration . Important partial differential equations include the heat equation, the wave equation, and Laplace's equation , which are central to mathematical physics .