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From Luc Maisonobe <Luc.Maison...@free.fr>
Subject Re: [math] Request: Othogonal polynomials
Date Thu, 29 Jan 2009 20:06:45 GMT
Gilles Sadowski a écrit :
> Hello.
> 
> Would you consider transferring the contents of the Mantissa "algebra"
> package to Commons-Math?

The orthogonal polynomials would be a nice addition. The current
implementation in Mantissa does not look good to me, after a few years.
The two internal classes Polynomial.Double and
Polynomial.RationalNumber, which are mimicked after the
java.awt.geom.Point2D class and its two Point2D.Double and Point2D.Float
classes seems clumsy now.

If we consider preserving two classes, one for double and another one
for computation, I wonder if we should not split them in parallel but
unrelated classes, just like RealMatrix and BigMatrix. We could add the
class with exact computation afterwards too, only if really needed.

I also wonder if dedicated classes are needed. Mantissa provides one
abstract base class OrhtogonalPolynomial and one class for each type
(Chebyshev, Legendre, Laguerre, Hermite). Could we simply use the
existing polynomials class and add a utility class PolynomialsUtils with
factory methods createXxxPolynomial() ? This utility class would cache
already computed coefficients as exact Fraction instances and create the
polynomials by converting the Fraction to simple double arrays at
construction time.

Any thoughts ?

Luc

> 
> Thanks,
> Gilles
> 
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