# How to calculate a integral on boundary

1. Mar 1, 2008

### Stole

Hi,
I would like to calculate the following integration:

\oint_{\Sigma}f(x,y)g(x,y)\mathbf{n}\cdot d\mathbf{s}

where g(x,y)=0 on \Sigma, and \mathbf{n} is the outward pointing unit normal field of the boundary \Sigma.

In this case does the integral equals to 0?

Thanks!

2. Mar 2, 2008

### HallsofIvy

Staff Emeritus
You forgot the [ tex ] and [ /tex ] tags!
Yes, if your integrand is always 0, the integral is 0. Isn't that obvious?