[R] isoMDS

Prof Brian Ripley ripley at stats.ox.ac.uk
Wed Sep 8 16:58:01 CEST 2004

On Wed, 8 Sep 2004, Hanke, Alex wrote:

> Distances cannot always be constructed from similarities. This can be done
> only if the matrix of similarities is nonnegative definite. With the
> nonnegative definite condition, and with the maximum similarity scaled so
> that s_ii=1, d_ik=(2*(1-s_ik))^-.5

But isoMDDS works with dissimilarities not distances.

Brian D. Ripley,                  ripley at stats.ox.ac.uk
Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
University of Oxford,             Tel:  +44 1865 272861 (self)
1 South Parks Road,                     +44 1865 272866 (PA)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595

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