[R] Understanding hclust and dendrogram

[Peng Yu]

On Thu, Oct 15, 2009 at 4:11 AM, Fearghas MacGregor
<fmacgregor at gmail.com> wrote:
> I'd recommend "The Elements of Statistical Learning" by Hastie, Tibshirani,
> and Friedman. There's a lot of good information on clustering, as well as a
> wealth of info on many other apsects of classification, machine learning,
> etc.
>
> I can be downoaded, free of charge, in PDF format, from:
> http://www-stat.stanford.edu/~tibs/ElemStatLearn/

One page 504, below eq(14.22) it mentioend 'if the inputs are first
standardized ...'

I'm not clear what it means and why $\sum_j(x_{ij}-x_{i'j})^2\prop
2(1-\rho(x_i,x_{i'})$?

Could somebody help understand it?