Vector notation for use in ray-sphere intersection

[poo2thegeek]

I need to find out if a ray intersects an object. The object is technically a cube, but  sphere can suffice as I believe ray-sphere intersection is more efficient than ray-cube intersection (also, i cannot find any good info about ray-cube intersection).
I have got most of the maths needed from the Wikipedia page 'Lineâ€"sphere_intersection' 
( http://en.wikipedia.org/wiki/Line%E2%80%93sphere_intersection )

But some of the stuff on the page doesn't seem to make much sense. For example, I can understand the first bit on the page that states taking the magnitude of (x-c)^2 = r^2, but later on the page tries to square raw vectors. For example, the very last bit of math is:
(o-c)^2 + r^2...
But o and c are vectors, so there is no way to square them is there? Unless I'm missing something else out of the page...
Thanks for any help explaining what I've done wrong!

[quew8]

Well r is the radius of the circle which makes it a plain old scalar. If you look carefully it is actually ( l . ( o - c ) ) ^ 2 (where . is the dot product) so that is also a scalar squared. If you don't understand any of the algebra, I would be happy to go through it with you (just ask) but I get the impression that your vector maths are a bit weak in general. If that's not the case I'm sorry, but if it is then I would recommend having a read of this: http://www.wildbunny.co.uk/blog/vector-maths-a-primer-for-games-programmers/. It's where I learnt everything I know on the subject.

[poo2thegeek]

Ah I figured it out myself eventually, thanks still for the help.
I understood it all. My only problem was the power of two, I didn't see the part on the page that stated this to be a dot product. I assumed it meant to square a vector, something you can't do.
For anyone who ever needs this in future, here was my final code:

public static boolean rayIntersectsSphere(Vector3f sphereC, float radius, 
			Vector3f ray, Vector3f pos){
		float underrt = (square(dot(ray,minus(pos,sphereC))))-dot(minus(pos,sphereC),minus(pos,sphereC)) + square(radius);
		if(underrt<0) return false;
		return true;
	}