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[Maxima-bugs] [ maxima-Bugs-831445 ] gcd/subres -- another case
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From: SourceForge.net <no...@so...> - 2007-07-23 12:31:21
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Bugs item #831445, was opened at 2003-10-27 18:44 Message generated for change (Comment added) made by dgildea You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=104933&aid=831445&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 Group: None Status: Open Resolution: None Priority: 5 Private: No Submitted By: Stavros Macrakis (macrakis) Assigned to: Nobody/Anonymous (nobody) Summary: gcd/subres -- another case Initial Comment: ratsimp of ((-SQRT(3)*%I/2-1/2)*(SQRT(84541)*%I/(6*SQRT(3))- 11/2)^(1/3)+28*(SQRT(3)*%I/2-1/2)/(3*(SQRT(84541) *%I/(6*SQRT(3))-11/2)^(1/3))+4)^3-12*((-SQRT(3)*% I/2-1/2)*(SQRT(84541)*%I/(6*SQRT(3))-11/2)^(1/3) +28*(SQRT(3)*%I/2-1/2)/(3*(SQRT(84541)*%I/ (6*SQRT(3))-11/2)^(1/3))+4)^2+20*((-SQRT(3)*%I/2- 1/2)*(SQRT(84541)*%I/(6*SQRT(3))-11/2)^(1/3)+28* (SQRT(3)*%I/2-1/2)/(3*(SQRT(84541)*%I/(6*SQRT (3))-11/2)^(1/3))+4)+59 gives "quotient by zero" for gcd = subres, red, or algebraic; and an infinite loop (or at least is taking a very long time) for mod. spmod and ez work. Maxima 5.9.0 gcl 2.5.0 ---------------------------------------------------------------------- >Comment By: Dan Gildea (dgildea) Date: 2007-07-23 08:31 Message: Logged In: YES user_id=1797506 Originator: NO subresgcd keeps taking remainders until it is left with a "common factor" of (#:|sqrt(3)1764| 1 1 0 (#:|3^(1/6)1763| 3 -1)) which it doesn't realize is zero. oldgcd attempts to divide this out and gets division by zero. ---------------------------------------------------------------------- Comment By: Robert Dodier (robert_dodier) Date: 2006-07-11 01:11 Message: Logged In: YES user_id=501686 Same behavior in 5.9.3cvs. ---------------------------------------------------------------------- Comment By: Stavros Macrakis (macrakis) Date: 2003-10-27 18:46 Message: Logged In: YES user_id=588346 By the way, all the gcd algorithms work correctly with algebraic:true (not the default). ---------------------------------------------------------------------- You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=104933&aid=831445&group_id=4933 |