From: SourceForge.net <no...@so...> - 2007-08-07 18:51:40
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Bugs item #1769598, was opened at 2007-08-07 13:51 Message generated for change (Tracker Item Submitted) made by Item Submitter You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=104933&aid=1769598&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 - Floating point Group: None Status: Open Resolution: None Priority: 7 Private: No Submitted By: Barton Willis (willisbl) Assigned to: Nobody/Anonymous (nobody) Summary: (negative float)^rational Initial Comment: negative float to a rational power is broken: (%i7) (-4.207913)^(2/3); (%o7) (0.25*26695^(2/3))/793^(2/3) (%i8) (-4.2079137)^(2/3); (%o8) (1.0*5849^(2/3))/1390^(2/3) (%i9) (-4.207)^(2/3); (%o9) 0.01*4207^(2/3) When 'float' is true, it's worse: (%i16) (-4.2079137)^(2/3); (%o16) (-4.2079137)^0.66666666666667 (%i17) rectform(%); (%o17) 2.25722671285884*%i-1.303210450291064 Since the exponent gets converted to a float, the real branch rule isn't an option. After that, rectform does the right thing. ---------------------------------------------------------------------- You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=104933&aid=1769598&group_id=4933 |
From: SourceForge.net <no...@so...> - 2007-11-18 20:27:07
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Bugs item #1769598, was opened at 2007-08-07 14:51 Message generated for change (Comment added) made by dgildea You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=104933&aid=1769598&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 - Floating point Group: None >Status: Closed >Resolution: Fixed Priority: 7 Private: No Submitted By: Barton Willis (willisbl) Assigned to: Nobody/Anonymous (nobody) Summary: (negative float)^rational Initial Comment: negative float to a rational power is broken: (%i7) (-4.207913)^(2/3); (%o7) (0.25*26695^(2/3))/793^(2/3) (%i8) (-4.2079137)^(2/3); (%o8) (1.0*5849^(2/3))/1390^(2/3) (%i9) (-4.207)^(2/3); (%o9) 0.01*4207^(2/3) When 'float' is true, it's worse: (%i16) (-4.2079137)^(2/3); (%o16) (-4.2079137)^0.66666666666667 (%i17) rectform(%); (%o17) 2.25722671285884*%i-1.303210450291064 Since the exponent gets converted to a float, the real branch rule isn't an option. After that, rectform does the right thing. ---------------------------------------------------------------------- >Comment By: Dan Gildea (dgildea) Date: 2007-11-18 15:27 Message: Logged In: YES user_id=1797506 Originator: NO Fixed in simp.lisp rev 1.44. (%i4) (-4.207913)^(2/3); (%o4) 2.606420611524446 (%i5) (-4.2079137)^(2/3); (%o5) 2.60642090058213 (%i6) (-4.207)^(2/3); (%o6) 2.606043584071641 (%i7) (-4.2079137)^(2/3),float; (%o7) (-4.2079137)^.6666666666666666 (%i8) (-4.2079137)^(2/3),float,numer_pbranch; (%o8) 2.25722671285884*%i-1.303210450291064 (%i9) (-4.2079137)^(2/3),numer_pbranch; (%o9) 2.60642090058213 ---------------------------------------------------------------------- You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=104933&aid=1769598&group_id=4933 |