# Strum Algorithm And Number of Distinct Roots

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## Strum Algorithm And Number of Distinct Roots

 Hi all,I have been playing with CGAL's polynomial utilities and I have a question.As far as I understand Strum's algorithm, it should calculate the exact number of distinct real roots. There is a polynomial however, where it overestimates the number of real roots, and when I calculate the roots, it repeated one of them, even though it wasn't a repeated root. Is this normal behavior?Thanks,Ahmed Essam
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## Re: Strum Algorithm And Number of Distinct Roots

 Is the root repeat a non degree 1 root? Do you have an example showing the problem? Best, Sebastien. On 3/5/20 1:08 PM, Ahmed Essam wrote: > Hi all, > > I have been playing with CGAL's polynomial utilities and I have a question. > As far as I understand Strum's algorithm, it should calculate the exact > number of distinct real roots. There is a polynomial however, where it > overestimates the number of real roots, and when I calculate the roots, > it repeated one of them, even though it wasn't a repeated root. Is this > normal behavior? > > Thanks, > Ahmed Essam -- You are currently subscribed to cgal-discuss. To unsubscribe or access the archives, go to https://sympa.inria.fr/sympa/info/cgal-discuss
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## Re: Strum Algorithm And Number of Distinct Roots

 It was the case with the bezier bug, I depended on visual representation. The output of the algorithm is correct, there were 3 different roots all very close to each other, that they were 'cout'ed as the same string. Mistake is on my part.Thanks,Ahmed Essam.On Wed, Mar 11, 2020, 9:45 AM Sebastien Loriot (GeometryFactory) <[hidden email]> wrote:Is the root repeat a non degree 1 root? Do you have an example showing the problem? Best, Sebastien. On 3/5/20 1:08 PM, Ahmed Essam wrote: > Hi all, > > I have been playing with CGAL's polynomial utilities and I have a question. > As far as I understand Strum's algorithm, it should calculate the exact > number of distinct real roots. There is a polynomial however, where it > overestimates the number of real roots, and when I calculate the roots, > it repeated one of them, even though it wasn't a repeated root. Is this > normal behavior? > > Thanks, > Ahmed Essam -- You are currently subscribed to cgal-discuss. To unsubscribe or access the archives, go to https://sympa.inria.fr/sympa/info/cgal-discuss