# Could we have a roots() method in PolynomilFunction class?

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## Could we have a roots() method in PolynomilFunction class?

 Hello Jira seems to be down? So I'm trying here to post my request for an enhancement: Could we have a roots() method in PolynomialFunction class? For example I ported the code in this stackoverflow question to apache commons math by using the EigenDecomposition class: http://stackoverflow.com/questions/13805644/finding-roots-of-polynomial-in-java/13805708#13805708See the attached file for an example. -- Axel Kramer Symja Library - Java Symbolic Math System https://bitbucket.org/axelclk/symja_android_library/wiki/Home--------------------------------------------------------------------- To unsubscribe, e-mail: [hidden email] For additional commands, e-mail: [hidden email] FindRoot.java (2K) Download Attachment
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## Re: Could we have a roots() method in PolynomilFunction class?

 On 06/27/2014 04:24 PM, Axel wrote: > Hello > > Jira seems to be down? > So I'm trying here to post my request for an enhancement: > > Could we have a roots() method in PolynomialFunction class? > For example I ported the code in this stackoverflow question to apache > commons math by using the EigenDecomposition class: > http://stackoverflow.com/questions/13805644/finding-roots-of-polynomial-in-java/13805708#13805708> > See the attached file for an example. Hi Alex, I did take a look at the stackoverflow question, and there is already a way to do this in Commons Math using the LaguerreSolver via the solveComplex and solveAllComplex methods. But it might be good to support a second way using EigenDecomposition as a stand-alone solver. I like the idea to add a roots() method to PolynomialFunction, but which method to compute the roots is more robust? Thomas --------------------------------------------------------------------- To unsubscribe, e-mail: [hidden email] For additional commands, e-mail: [hidden email]
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## Re: Could we have a roots() method in PolynomilFunction class?

 On Fri, Jun 27, 2014 at 10:56 PM, Thomas Neidhart <[hidden email]> wrote: ... > I did take a look at the stackoverflow question, and there is already a > way to do this in Commons Math using the LaguerreSolver via the > solveComplex and solveAllComplex methods. > > But it might be good to support a second way using EigenDecomposition as > a stand-alone solver. > > I like the idea to add a roots() method to PolynomialFunction, but which > method to compute the roots is more robust? The attached link in the stackoverflow question to this paper: http://techdigest.jhuapl.edu/TD/td2804/Williams.pdfhas this conclusion: "We have discussed some eigenvector methods for finding the roots of multi- variate polynomials. Unlike iterative, numerical methods typically applied to this problem, the methods outlined in this article possess the numerical stability of numerical linear algebra, do not require a good initial guess of the solution, and give all solutions simultaneously. Furthermore, if the initial guess is poor enough, the methods outlined herein may converge more quickly than iterative methods." So I think the "EigenDecomposition method" is more appropriate if you don't have an initial guess to start from getting the roots!? -- Axel Kramer --------------------------------------------------------------------- To unsubscribe, e-mail: [hidden email] For additional commands, e-mail: [hidden email]
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## Re: Could we have a roots() method in PolynomilFunction class?

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## Re: Could we have a roots() method in PolynomilFunction class?

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