Stas Kolenikov <[email protected]> asks:
> is there an easy way to code the distance between two points on the Earth
> surface along the great-circle arc given their longitudes and latitudes? I
> want to cluster a few geographical locations... I know a messy way to do
> it -- to go through all 2400 lines of cluster.ado and find out where the
> (dis)similarity measures are computed, and make a new one that I need. (Is
> this possible with the programmer's extensions to cluster that Stata
> provides for, instead? I looked it up rather quickly, and decided it is
> not quite what I need.) My gut feeling though is that it is the
> responsibility of the built-in -_cluster-, so there is not much I can do
> to define my own distance function, is there?
The distance calculations are done in C code, and so not
alterable by users. There are many distance, dissimilarity, and
similarity measures available, but not the one you mention in
your note.
Ken Higbee [email protected]
StataCorp 1-800-STATAPC
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