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From: SourceForge.net <noreply@so...>  20031008 19:46:04

Bugs item #820188, was opened at 20031008 15:46 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=820188&group_id=4933 Category: None Group: None Status: Open Resolution: None Priority: 5 Submitted By: Stavros Macrakis (macrakis) Assigned to: Nobody/Anonymous (nobody) Summary: Simplifying inf and minf Initial Comment: The general simplifier currently treats the various non standard objects (inf, minf, und, ind, infinity) as though they were ordinary variables. This leads to incorrect results (infinf => 0, inf*0 => 0), incomplete simplification (inf^3 doesn't simplify, though inf is always correct), and noncanonical representations (minf doesn't simplify to inf). It also seems to me that minf should be represented uniformly as inf, not as a special case. Specialcasing these objects in the general simplifier will add a very small overhead to all simplifications. The case that reminded me of this problem is abs(minf) =>minf.  You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=104933&aid=820188&group_id=4933 
From: SourceForge.net <noreply@so...>  20040321 21:10:07

Bugs item #820188, was opened at 20031008 15:46 Message generated for change (Comment added) made by macrakis You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=104933&aid=820188&group_id=4933 Category: None Group: None Status: Open Resolution: None Priority: 5 Submitted By: Stavros Macrakis (macrakis) Assigned to: Nobody/Anonymous (nobody) Summary: Simplifying inf and minf Initial Comment: The general simplifier currently treats the various non standard objects (inf, minf, und, ind, infinity) as though they were ordinary variables. This leads to incorrect results (infinf => 0, inf*0 => 0), incomplete simplification (inf^3 doesn't simplify, though inf is always correct), and noncanonical representations (minf doesn't simplify to inf). It also seems to me that minf should be represented uniformly as inf, not as a special case. Specialcasing these objects in the general simplifier will add a very small overhead to all simplifications. The case that reminded me of this problem is abs(minf) =>minf.  >Comment By: Stavros Macrakis (macrakis) Date: 20040321 16:10 Message: Logged In: YES user_id=588346 More problematic cases with inverse functions: asin(sin(inf)) => inf This should either not simplify, or give IND (if it is clever) or UND (if it is less clever). but exp(log(inf)) => inf tan(atan(inf)) => inf and the like are OK (by accident, but, hey!)  You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=104933&aid=820188&group_id=4933 
From: SourceForge.net <noreply@so...>  20060711 04:36:31

Bugs item #820188, was opened at 20031008 13:46 Message generated for change (Settings changed) made by robert_dodier You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=104933&aid=820188&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  Simplification Group: None Status: Open Resolution: None Priority: 5 Submitted By: Stavros Macrakis (macrakis) Assigned to: Nobody/Anonymous (nobody) Summary: Simplifying inf and minf Initial Comment: The general simplifier currently treats the various non standard objects (inf, minf, und, ind, infinity) as though they were ordinary variables. This leads to incorrect results (infinf => 0, inf*0 => 0), incomplete simplification (inf^3 doesn't simplify, though inf is always correct), and noncanonical representations (minf doesn't simplify to inf). It also seems to me that minf should be represented uniformly as inf, not as a special case. Specialcasing these objects in the general simplifier will add a very small overhead to all simplifications. The case that reminded me of this problem is abs(minf) =>minf.  Comment By: Stavros Macrakis (macrakis) Date: 20040321 14:10 Message: Logged In: YES user_id=588346 More problematic cases with inverse functions: asin(sin(inf)) => inf This should either not simplify, or give IND (if it is clever) or UND (if it is less clever). but exp(log(inf)) => inf tan(atan(inf)) => inf and the like are OK (by accident, but, hey!)  You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=104933&aid=820188&group_id=4933 
From: SourceForge.net <noreply@so...>  20080405 22:37:27

Bugs item #820188, was opened at 20031008 13:46 Message generated for change (Comment added) made by robert_dodier You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=104933&aid=820188&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  Simplification Group: None Status: Open Resolution: None >Priority: 7 Private: No Submitted By: Stavros Macrakis (macrakis) Assigned to: Nobody/Anonymous (nobody) Summary: Simplifying inf and minf Initial Comment: The general simplifier currently treats the various non standard objects (inf, minf, und, ind, infinity) as though they were ordinary variables. This leads to incorrect results (infinf => 0, inf*0 => 0), incomplete simplification (inf^3 doesn't simplify, though inf is always correct), and noncanonical representations (minf doesn't simplify to inf). It also seems to me that minf should be represented uniformly as inf, not as a special case. Specialcasing these objects in the general simplifier will add a very small overhead to all simplifications. The case that reminded me of this problem is abs(minf) =>minf.  >Comment By: Robert Dodier (robert_dodier) Date: 20080405 16:37 Message: Logged In: YES user_id=501686 Originator: NO Increasing the priority of this item. See also [ 1562671 ] Handling of infinities.  Comment By: Stavros Macrakis (macrakis) Date: 20040321 14:10 Message: Logged In: YES user_id=588346 More problematic cases with inverse functions: asin(sin(inf)) => inf This should either not simplify, or give IND (if it is clever) or UND (if it is less clever). but exp(log(inf)) => inf tan(atan(inf)) => inf and the like are OK (by accident, but, hey!)  You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=104933&aid=820188&group_id=4933 