a question on proot

Librairie C++ de calcul formel/ C++ symbolic computation library

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a question on proot

Message par jocaps » dim. déc. 17, 2017 6:45 am


I am trying to understand the code behind proot. But I don't think I would understand it in a very short time. I just want to confirm one thing, maybe someone could help answering this question:

Suppose I have an irreducible polynomial of degree 2d in one variable (coefficients are all integers) and such that roots are all non-real and have multiplicity 1. Is it true that proot outputs the roots as conjugate pairs in sequence. What I mean is that is it true that the output of proot is:

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[z1,conj(z1),z2,conj(z2),..., zd,conj(zd)]
where zi, i=1,..,d are distinct complex roots. I have the impression that this is true (if so I do not need to write an extra code finding where the imaginary conjugates are).


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Re: a question on proot

Message par parisse » lun. déc. 18, 2017 7:18 pm

The code of proot is unfortunately hard to read, because there are several algorithms involved, mixing symbolic methods (for multiplicities), numeric with library calls (GSL, PARI) and numeric built-in. I can not warrant that you will always get pairs of conjugate one after the other one...