[R] spherical coordinates and quadratic regression
spencer.graves at pdf.com
Sun Feb 23 00:50:04 CET 2003
What functions are available to support working in spherical
coordinates, e.g., transforming (x, y, z) on a unit sphere to
(longitude, latitude) and vice versa?
More generally, is anything available on quadratic regression, i.e.,
obtaining a least squares solution to a system of n equations quadratic
in 3 unknowns? The sum of squares of residuals (SSE) can have either
one or two local minima. With polar coordinates, I can tell if a
solution is unique and find the other solution if it is not.
I can write my own, but I'd rather use more standard utilities if
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