Mathematics desk
< June 13	<< May \| June \| Jul >>	June 15 >

Welcome to the Wikipedia Mathematics Reference Desk Archives
The page you are currently viewing is an archive page. While you can leave answers for any questions shown below, please ask new questions on one of the current reference desk pages.

June 14[edit]

n in definition of Green's theorem[edit]

In the following identity, $\int \int \int _{V}\phi div(grad(\psi ))+grad(\phi )\cdot grad(\psi )dV=\int \int _{S}\phi {\frac {\partial \psi }{\partial n}}dS$ , what does $n$ represent? ? Widener (talk) 20:40, 14 June 2012 (UTC)[reply]

It represents a normal -- this is the directional derivative in the direction perpendicular to the surface. Looie496 (talk) 21:18, 14 June 2012 (UTC)[reply]