>>>>> "HenrikB" == Henrik Bengtsson <

[hidden email]>

>>>>> on Wed, 14 Dec 2005 17:05:32 +1100 writes:

HenrikB> Hi,

HenrikB> help on 'mahalanobis' (in the stats package in Rv2.2.0) now says:

HenrikB> "Description:

HenrikB> Returns the Mahalanobis distance of all rows in 'x' and the vector

HenrikB> mu='center' with respect to Sigma='cov'. This is (for vector 'x')

HenrikB> defined as

HenrikB> D^2 = (x - mu)' Sigma^{-1} (x - mu)"

HenrikB> It does return D^2 as written. However, would the

HenrikB> text be more clear if it says "Returns the

HenrikB> _squared_ Mahalanobis distance D^2..." instead? If

HenrikB> so, then text in the example code, e.g. "##- Here,

HenrikB> D^2 = usual Euclidean distances" and the title of

HenrikB> the first plot will also have to be updated.

Indeed, thank you!

Committed {even to R-beta}.

HenrikB> Compare this with what dist() in the same package

HenrikB> returns. When asking for the Equlidean distance

HenrikB> (matrix) between rows in a matrix, we get D not

HenrikB> D^2, e.g. dist(c(1,3)) == 2.

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