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From: SourceForge.net <noreply@so...>  20100602 16:15:49

Bugs item #3010567, was opened at 20100602 16:15 Message generated for change (Tracker Item Submitted) made by nobody You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=104933&aid=3010567&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  Solving equations Group: None Status: Open Resolution: None Priority: 5 Private: No Submitted By: Nobody/Anonymous (nobody) Assigned to: Nobody/Anonymous (nobody) Summary: bug in find_root; Initial Comment: Bug in find_root, probably by overflow. It finds a completely wrong solution without warning.  You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=104933&aid=3010567&group_id=4933 
From: SourceForge.net <noreply@so...>  20100602 18:22:52

Bugs item #3010567, was opened at 20100602 12:15 Message generated for change (Comment added) made by rtoy You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=104933&aid=3010567&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  Solving equations Group: None Status: Open Resolution: None Priority: 5 Private: No Submitted By: Nobody/Anonymous (nobody) Assigned to: Nobody/Anonymous (nobody) Summary: bug in find_root; Initial Comment: Bug in find_root, probably by overflow. It finds a completely wrong solution without warning.  >Comment By: Raymond Toy (rtoy) Date: 20100602 14:22 Message: Yes, it's an overflow problem. (I get an overflow error with cmucl). For the record, here is the function: F(x,y):=(log(x)/log(y))^xx^(log(x)/log(y)); F(400,y) is log(400)^400/log(y)^400x^(log(400)/log(2)). log(400)^400 overflows. Maxima changed (log(x)/log(y))^x to log(x)^x/log(y)^x, which causes the problem.  You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=104933&aid=3010567&group_id=4933 
From: SourceForge.net <noreply@so...>  20101005 13:55:37

Bugs item #3010567, was opened at 20100602 12:15 Message generated for change (Comment added) made by rtoy You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=104933&aid=3010567&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  Solving equations Group: None >Status: Pending >Resolution: Wont Fix Priority: 5 Private: No Submitted By: Nobody/Anonymous (nobody) Assigned to: Nobody/Anonymous (nobody) Summary: bug in find_root; Initial Comment: Bug in find_root, probably by overflow. It finds a completely wrong solution without warning.  >Comment By: Raymond Toy (rtoy) Date: 20101005 09:55 Message: I'm inclined to think this is something that is not maxima's problem. When doing numerical work, some thinking about numerical issues is required, and avoiding overflow is something that needs to be considered. That maxima didn't catch the overflow is not maxima's fault but the underlying lisp, since cmucl did signal an overflow. Also, in the latest CVS version, there is bf_find_root which will use bfloats which do not overflow. Due to a bug, bf_find_root can't solve this either, but when the bug is fixed, the root is found. Hence, marking this as pending/wontfix.  Comment By: Raymond Toy (rtoy) Date: 20100602 14:22 Message: Yes, it's an overflow problem. (I get an overflow error with cmucl). For the record, here is the function: F(x,y):=(log(x)/log(y))^xx^(log(x)/log(y)); F(400,y) is log(400)^400/log(y)^400x^(log(400)/log(2)). log(400)^400 overflows. Maxima changed (log(x)/log(y))^x to log(x)^x/log(y)^x, which causes the problem.  You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=104933&aid=3010567&group_id=4933 
From: SourceForge.net <noreply@so...>  20101019 14:20:05

Bugs item #3010567, was opened at 20100602 16:15 Message generated for change (Comment added) made by sfrobot You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=104933&aid=3010567&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  Solving equations Group: None >Status: Closed Resolution: Wont Fix Priority: 5 Private: No Submitted By: Nobody/Anonymous (nobody) Assigned to: Nobody/Anonymous (nobody) Summary: bug in find_root; Initial Comment: Bug in find_root, probably by overflow. It finds a completely wrong solution without warning.  >Comment By: SourceForge Robot (sfrobot) Date: 20101019 14:20 Message: This Tracker item was closed automatically by the system. It was previously set to a Pending status, and the original submitter did not respond within 14 days (the time period specified by the administrator of this Tracker).  Comment By: Raymond Toy (rtoy) Date: 20101005 13:55 Message: I'm inclined to think this is something that is not maxima's problem. When doing numerical work, some thinking about numerical issues is required, and avoiding overflow is something that needs to be considered. That maxima didn't catch the overflow is not maxima's fault but the underlying lisp, since cmucl did signal an overflow. Also, in the latest CVS version, there is bf_find_root which will use bfloats which do not overflow. Due to a bug, bf_find_root can't solve this either, but when the bug is fixed, the root is found. Hence, marking this as pending/wontfix.  Comment By: Raymond Toy (rtoy) Date: 20100602 18:22 Message: Yes, it's an overflow problem. (I get an overflow error with cmucl). For the record, here is the function: F(x,y):=(log(x)/log(y))^xx^(log(x)/log(y)); F(400,y) is log(400)^400/log(y)^400x^(log(400)/log(2)). log(400)^400 overflows. Maxima changed (log(x)/log(y))^x to log(x)^x/log(y)^x, which causes the problem.  You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=104933&aid=3010567&group_id=4933 
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