--- Phil Steitz <[EMAIL PROTECTED]> wrote:
> 
> 
> > I missed the beginning of this thread; my Yahoo mail has been strangely low
> in
> > activity the past two days.
> > 
> > Rather than espouse an opinion on where these methods should go, let me ask
> why
> > a parallel sort would be so bad.  Especially if you sorted by using an
> index
> > table.  I did a clean-room implementation of index table sorting in Ruby a
> few
> > weeks ago for my wife, based on the text description of the algorithm in
> _NR_
> > (I was very careful not to read the code -- though I'm pretty sure I had to
> > type it in once and use it years ago in grad school, I sure wouldn't
> remember
> > even a line of it now).
> 
> The use case that touched this off was validating the knot point array 
> passed in to spline interpolation.  If the x[] values are not strictly 
> increasing, the activation is suspect, so I would prefer to throw rather 
> than speculatively sort the y[] vector in parallel. Same problem applies 
> to the constructor of the PolynomialSpline wrt x[] and polynomials[] 
> (where parallel sorting would be even more dubious).
> 
> Phil

It just occurred to me that a use case that perhaps we have not considered is
in graphics and scalable fonts, where relations that are not functions (i.e.,
they are multi-valued functions) can easily occur -- think of your favorite
drawing program's ability to draw Bezier curves with loops in them.  I know
that font systems use cubic (Postscript) and quadratic (TrueType) curves to
describe font outlines -- though that case doesn't necessarily argue for
multivalued interpolating segments.

Anyway, food for thought.


Al

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