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From Luc Maisonobe <>
Subject Re: [Math] PolynomialFunctionLagrangeForm (continued)
Date Sun, 31 Oct 2010 14:57:33 GMT
Le 31/10/2010 15:08, Gilles Sadowski a écrit :
> Hi.
> [Continued from the previous message.]
> Accepting that the interpolation abscissae are not sorted in strictly
> increasing order make it necessary to check (at every call to the "value"
> method) that no 2 interpolating points are the same.
> The code would be cleaner is we assume (as a pre-condition) that the "x"
> interval is sorted. [And it would be more similar to other interpolating
> classes that explicitely prohibit unsorted interpolation intervals.]

So I guess you would put this check in the verifyInterpolationArray
method which is called from constructor and remove the d == 0 check in
computeCoefficient ?

Beware that the static evaluate method can be called directly from
outside. We need to keep this public method, so we may perhaps split it
as a check followed by a call to a private internal method that does no
check, whereas the value instance method would directly call the
no-check version since the check would have been done beforehand in the


> If we nevertheless want to allow the user to pass an unsorted interval, I'd
> rather have a new utility method that would sort the "x" interval (and apply
> the corresponding permutations to "y") within the constructor.
> Gilles
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