Thanks :)
It's actually in Cartesian coordinates, x and y (it's 2d, not 3d). When I calculate this function, I first compute the distance from 0,0 to x,y, and assign that to 'r'. 'h' is a constant (representing the size of the kernel I'm applying).
So maybe I want something like...
Simple gradient question.. I have a kernel function that determines the influence of each water droplet given a radius r:
(10/pi*h^5)*(h-r)^3
The gradient of that is:
(-30/pi*h^5)*(h-r)^2
But 'r' is not a vector, its a scalar, its just the distance to the point in question. So how do...