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A separable partial differential equation (PDE) is one that can be broken into a set of separate equations of lower dimensionality (fewer independent variables) by a method of separation of variables. This generally relies upon the problem having some special form or symmetry. In this way, the PDE can be solved by solving a set of simpler PDEs, or even ordinary differential equations (ODEs) if the problem can be broken down into one-dimensional equations. The most common form of separation of variables is simple separation of variables in which a solution is obtained by assuming a solution of the form given by a product of functions of each individual coordinate.There is a special form of separation of variables called -separation of variables which is accomplished by writing the solution as a particular fixed function of the coordinates multiplied by a product of functions of each individual coordinate. Laplace's equation on is an example of a partial differential equation which admits solutions through -separation of variables; in the three-dimensional case this uses 6-sphere coordinates. (This should not be confused with the case of a separable ODE, which refers to a somewhat different class of problems that can be broken into a pair of integrals; see separation of variables.) == Example == For example, consider the time-independent Schrödinger equation : for the function (in dimensionless units, for simplicity). (Equivalently, consider the inhomogeneous Helmholtz equation.) If the function in three dimensions is of the form : then it turns out that the problem can be separated into three one-dimensional ODEs for functions , , and , and the final solution can be written as . (More generally, the separable cases of the Schrödinger equation were enumerated by Eisenhart in 1948.〔L. P. Eisenhart, "Enumeration of potentials for which one-particle Schrodinger equations are separable," ''Phys. Rev.'' 74, 87-89 (1948).〕) 抄文引用元・出典: フリー百科事典『 ウィキペディア(Wikipedia)』 ■ウィキペディアで「Separable partial differential equation」の詳細全文を読む スポンサード リンク
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