From: SourceForge.net <no...@so...> - 2010-01-20 14:01:59
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Bugs item #2935631, was opened at 2010-01-20 09:01 Message generated for change (Tracker Item Submitted) made by rtoy You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=104933&aid=2935631&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: 5 Private: No Submitted By: Raymond Toy (rtoy) Assigned to: Nobody/Anonymous (nobody) Summary: bfloat(log(n)) can be different from log(bfloat(n)) Initial Comment: bfloat(log(n)) uses logbigfloat, which calls fplog to compute the result. log(bfloat(n)) uses big-float-log to compute the result using the property log(f*2^m) = log(f)+m*log(2). Since the algorithms are different, the result of bfloat(log(n)) and log(bfloat(n)) could be different. I suggest changing logbigfloat to call big-float-log so that the results are guaranteed to be the same. ---------------------------------------------------------------------- You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=104933&aid=2935631&group_id=4933 |
From: SourceForge.net <no...@so...> - 2010-01-21 00:48:06
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Bugs item #2935631, was opened at 2010-01-20 09:01 Message generated for change (Settings changed) made by rtoy You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=104933&aid=2935631&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: 5 Private: No Submitted By: Raymond Toy (rtoy) Assigned to: Nobody/Anonymous (nobody) Summary: bfloat(log(n)) can be different from log(bfloat(n)) Initial Comment: bfloat(log(n)) uses logbigfloat, which calls fplog to compute the result. log(bfloat(n)) uses big-float-log to compute the result using the property log(f*2^m) = log(f)+m*log(2). Since the algorithms are different, the result of bfloat(log(n)) and log(bfloat(n)) could be different. I suggest changing logbigfloat to call big-float-log so that the results are guaranteed to be the same. ---------------------------------------------------------------------- >Comment By: Raymond Toy (rtoy) Date: 2010-01-20 19:48 Message: Fixed. logbigfloat calls big-float-log as needed. ---------------------------------------------------------------------- You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=104933&aid=2935631&group_id=4933 |