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[Maxima-bugs] [ maxima-Bugs-2894516 ] Bad ratinal solution
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From: SourceForge.net <no...@so...> - 2009-11-09 15:06:21
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Bugs item #2894516, was opened at 2009-11-09 06:54 Message generated for change (Settings changed) made by rtoy You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=104933&aid=2894516&group_id=4933 Please note that this message will contain a full copy of the comment thread, including the initial issue submission, for this request, not just the latest update. Category: Lisp Core - Polynomials Group: None >Status: Pending >Resolution: Invalid Priority: 5 Private: No Submitted By: Nobody/Anonymous (nobody) Assigned to: Nobody/Anonymous (nobody) Summary: Bad ratinal solution Initial Comment: I try to find a real root of x^3-2*x^2-x-1. To do that i search a rational number a/b, root of the polynom, id est a couple of integers (a,b) verifying a^3-2ba^2-ab^2=15b^3 ; a classical use of Excel or OO3 calc give me (a/b) with 8 or 14 decimals, and the doubt : is there a RATIONAL root ? I open Wxmaxima and ask realroot(x^3-2x^2-x-1) : the answer is rational (see attached file) BUT !!! the given terms a and b don't verify the relation above !!!!! ---------------------------------------------------------------------- >Comment By: Raymond Toy (rtoy) Date: 2009-11-09 10:06 Message: Marking as pending/invalid. ---------------------------------------------------------------------- Comment By: Raymond Toy (rtoy) Date: 2009-11-09 10:05 Message: Please read the documentation of what realroots does: Computes rational approximations of the real roots of the polynomial <expr> or polynomial equation <eqn> of one variable, to within a tolerance of <bound>. Coefficients of <expr> or <eqn> If you want to know the exact roots, solve(x^3-2*x^2-x-1) will tell you. It appears there is no rational root. ---------------------------------------------------------------------- You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=104933&aid=2894516&group_id=4933 |
