Re: A question or two re: splines

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#644

From: J E H Shaw
Date: Tue, 06 Oct 1992 16:46

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Sorry - my e-mailed reply bounced, so I'm posting this (reply to
how to fit splines with a fixed number of free knots).

  I looked (briefly!) at this a long time ago.  With free knots,
  the equations are horribly ill-conditioned.  I think your best
  chance of fitting a spline in practice is iterative ad-hockery:
  fix the knots & fit the spline, find the `least important'
  knot (e.g. where the n'th deriv. changes least or the knot whose
  omission changes the likelihood least) & try it somewhere else
  (e.g. in the middle of the section with largest n'th deriv.)
  and repeat.  Or something like that.  Good luck.
                -- Ewart Shaw

I'll try to dig up whatever references I found on the problem.
-- 
J.E.H.Shaw,  Department of Statistics,  |  JANET:  strgh@uk.ac.warwick.cu
             University of Warwick,     |  BITNET: strgh%uk.ac.warwick.cu@UKACRL
             Coventry  CV4 7AL,  U.K.   |  PHONE:  +44 203 523069
Sarah (20 months) on first seeing juggling:  `Balls skipping in the sky'.

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Path: arc1-ca.pugleaf.net!sparky!uunet!pipex!warwick!strgh
From: strgh@warwick.ac.uk (J E H Shaw)
Subject: Re: A question or two re: splines
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Date: Tue, 6 Oct 1992 16:46:54 GMT
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