Laplacian: Difference between revisions

From Citizendium
Jump to navigation Jump to search
imported>Gemma E. Mason
(Notation and definition in Cartesian, spherical and cylindrical co-ordinates.)
 
imported>Gemma E. Mason
m (turned "spherical coordinates" and "cylindrical coordinates" into links)
Line 3: Line 3:
where <math>x_{i}</math> are Cartesian (that is, rectangular) co-ordinates.  The Laplacian is usually denoted by the symbol <math>\Delta</math> or written as the gradient squared <math>\nabla^{2}</math>.
where <math>x_{i}</math> are Cartesian (that is, rectangular) co-ordinates.  The Laplacian is usually denoted by the symbol <math>\Delta</math> or written as the gradient squared <math>\nabla^{2}</math>.


In cylindrical co-ordinates, the Laplacian takes the form<br />
In [[cylindrical coordinates]], the Laplacian takes the form<br />
<math>\frac{1}{\rho}\frac{\partial}{\partial \rho}\bigl(\rho\frac{\partial}{\partial\rho}\bigr)+\frac{1}{\rho^{2}}\frac{\partial^{2}}{\partial\phi^{2}}+\frac{\partial^{2}}{\partial z^{2}}</math><br />
<math>\frac{1}{\rho}\frac{\partial}{\partial \rho}\bigl(\rho\frac{\partial}{\partial\rho}\bigr)+\frac{1}{\rho^{2}}\frac{\partial^{2}}{\partial\phi^{2}}+\frac{\partial^{2}}{\partial z^{2}}</math><br />


In spherical co-ordinates, the Laplacian is<br/>
In [[spherical co-ordinates]], the Laplacian is<br/>
<math>\frac{1}{\rho^{2}}\frac{\partial}{\partial \rho}\bigl(\rho^{2}\frac{\partial}{\partial\rho}\bigr)+\frac{1}{\rho^{2}\mathrm{sin}\theta}\frac{\partial}{\partial\theta}\bigl(\mathrm{sin}\theta\frac{\partial}{\partial\theta}\bigr)+\frac{1}{\rho^{2}\mathrm{sin}^{2}\theta}\frac{\partial^{2}}{\partial\phi^{2}}</math>
<math>\frac{1}{\rho^{2}}\frac{\partial}{\partial \rho}\bigl(\rho^{2}\frac{\partial}{\partial\rho}\bigr)+\frac{1}{\rho^{2}\mathrm{sin}\theta}\frac{\partial}{\partial\theta}\bigl(\mathrm{sin}\theta\frac{\partial}{\partial\theta}\bigr)+\frac{1}{\rho^{2}\mathrm{sin}^{2}\theta}\frac{\partial^{2}}{\partial\phi^{2}}</math>

Revision as of 01:13, 3 September 2010

The Laplacian is a differential operator of the form

where are Cartesian (that is, rectangular) co-ordinates. The Laplacian is usually denoted by the symbol or written as the gradient squared .

In cylindrical coordinates, the Laplacian takes the form

In spherical co-ordinates, the Laplacian is