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[Maxima-bugs] [ maxima-Bugs-2592250 ] lmin
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From: SourceForge.net <no...@so...> - 2009-02-13 03:38:40
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Bugs item #2592250, was opened at 2009-02-12 02:42 Message generated for change (Comment added) made by willisbl You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=104933&aid=2592250&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: None Group: None Status: Open Resolution: None Priority: 5 Private: No Submitted By: Ago77 (ago77) Assigned to: Nobody/Anonymous (nobody) Summary: lmin Initial Comment: I came across a list that seems to expose a bug in "lmin." The list is: Q: [0, (10*sqrt(3019)-653)/(10*sqrt(3019)-800), -(1243*sqrt(3019)-65630)/(1600*sqrt(3019)-94190), (12270806*sqrt(3019)-674213245)/(15070400*sqrt(3019)-830019805), -(1534218310305203*sqrt(3019)-84298201004276722)/(2001396875083520*sqrt(3019)-109967917387142242), (877822352489691153078985106965453*sqrt(3019)-48232324401355597222123482321934010)/ (1100447231090345843897339350259200*sqrt(3019)-60464543522069663495052507120510410)]$ lmin(Q); produces a "Division by 0" error message - on the other hand, lmin(float(Q)); or also lmin(Q), numer; both yield - 0.089597918818624. lmax(Q) works properly, but -lmax(-Q) also yields a "Divide by 0" error, not too surprisingly. ---------------------------------------------------------------------- >Comment By: Barton Willis (willisbl) Date: 2009-02-12 21:38 Message: I believe the trouble is in computing the sign of: (%i62) (94648962737729943093436340438935374529647608621614*sqrt(3019)-5200527717336367518913170807682526084100767540599370)/(60506859663968574059067272189736794088560937142400*sqrt(3019)-3324575269180571635805235048597996242355104695758805); (%o62) (94648962737729943093436340438935374529647608621614*sqrt(3019)-5200527717336367518913170807682526084100767540599370)/(60506859663968574059067272189736794088560937142400*sqrt(3019)-3324575269180571635805235048597996242355104695758805) (%i63) sign(%); Division by 0 The number is actually not so complicated: (%i64) ratsimp(%o62), algebraic : true; (%o64) -(2*sqrt(3019)-70)/115 (%i65) sign(%); (%o65) neg ---------------------------------------------------------------------- Comment By: Barton Willis (willisbl) Date: 2009-02-12 21:34 Message: A workaround it to set algebraic : true. ---------------------------------------------------------------------- Comment By: Barton Willis (willisbl) Date: 2009-02-12 21:24 Message: A workaround it to set algebraic : true. ---------------------------------------------------------------------- You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=104933&aid=2592250&group_id=4933 |