Heat equation - Wikipedia
https://en.wikipedia.org/wiki/Heat_equationIn mathematics, if given an open subset U of R and a subinterval I of R, one says that a function u : U × I → R is a solution of the heat equation if where (x1, …, xn, t) denotes a general point of the domain. It is typical to refer to t as "time" and x1, …, xn as "spatial variables," even in abstract contexts where these phrases fail to have their intuitive meaning. The collection of spatial variables is often referred to simply as x. For any give…