haha, thanks for the math, i almost forget
> Date: Fri, 4 Nov 2011 16:01:02 +0100
> From: s...@apache.org
> To: user@mahout.apache.org
> Subject: Re: Can anybody explain the distance method in
> SquaredEuclideanDistanceMeasure?
>
> c = centroid
> v = vector
>
> (c - v)^2 = c^2 - 2cv + v^2
>
> On 04.11.2011 15:58, WangRamon wrote:
> >
> >
> >
> >
> > Hi All I'm reading the code of SquaredEuclideanDistanceMeasure, the
> > "distance(double centroidLengthSquare, Vector centroid, Vector v)" method
> > confused me a lot, i don't know why we choose this expression
> > "centroidLengthSquare - 2 * v.dot(centroid) + v.getLengthSquared()" to
> > calculate the distance? What is the best case to use this Measure? BTW, I
> > think it would be great if we can have a wiki or some detail user guide or
> > more comments in the source code to explain each distance measure
> > implementation, that will really help, thanks guys. Cheers Ramon
> >
