Looking around the Internet, I was a little disappointed to find that blogger doesn't natively support Latex. Fortunately there's a nifty program that you can run on a web server that will output latex code as a png.
Let
and
. Then either
or
.
The two dimentional gradient vector for a function u(x, y) is,
.
All made possible thanks to http://www.forkosh.com/mathtex.html - cheers!