From: SourceForge.net <no...@so...> - 2009-01-17 22:46:24
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Bugs item #626760, was opened at 2002-10-22 10:19 Message generated for change (Comment added) made by crategus You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=104933&aid=626760&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 Group: None >Status: Pending >Resolution: Wont Fix Priority: 5 Private: No Submitted By: Stavros Macrakis (macrakis) Assigned to: Nobody/Anonymous (nobody) Summary: zeroequiv extremely slow (minor) Initial Comment: expr: LOG(x^2+SQRT(2)*x+1) -LOG(x^2-SQRT(2)*x+1) +2*ATAN((2*x+SQRT(2))/SQRT(2)) +2*ATAN((2*x-SQRT(2))/SQRT(2)) +SQRT(2)*LOG(x+1) -SQRT(2)*LOG(x-1) -2*SQRT(2)*ATAN(1/x)$ zeroequiv(expr,x) takes over a minute, though it is not at all subtle how non-zero it is: rectform(expr),numer, ..., x=0.1 => -3.31-4.44i ..., x=0.9 => 6.39-4.44i ..., x=1.1 => 7.38 ..., x=1.5 => 6.38 ..., x=20 => 6.28 Zeroequiv is really supposed to be quick and dirty.... ---------------------------------------------------------------------- >Comment By: Dieter Kaiser (crategus) Date: 2009-01-17 22:35 Message: This bug report is related to SF[593530] "Zeroequiv issues". zeroequiv is not used for in core functions. Problems are known and documented. This is the result for the example: (%i9) expr:LOG(x^2+SQRT(2)*x+1)-LOG(x^2-SQRT(2)*x+1)+2*ATAN((2*x+SQRT(2))/SQRT(2)) +2*ATAN((2*x-SQRT(2))/SQRT(2))+SQRT(2)*LOG(x+1) -SQRT(2)*LOG(x-1)-2*SQRT(2)*ATAN(1/x) (%i10) zeroequiv(expr,x); (%o10) dontknow On a Windows system with GCL 2.6.8 and a CPU with 1.8 GHZ we get (%i11) for i:1 thru 100000 do zeroequiv(expr,x); Evaluation took 15.8900 seconds (15.8900 elapsed) (%o11) done One call to zeroequiv needs about 16/100,000 seconds. Setting resolution to "wont fix" and status to pending. Dieter Kaiser ---------------------------------------------------------------------- You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=104933&aid=626760&group_id=4933 |
From: SourceForge.net <no...@so...> - 2009-01-17 22:46:50
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Bugs item #626760, was opened at 2002-10-22 04:19 Message generated for change (Comment added) made by macrakis You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=104933&aid=626760&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 Group: None >Status: Closed >Resolution: Fixed Priority: 5 Private: No Submitted By: Stavros Macrakis (macrakis) Assigned to: Nobody/Anonymous (nobody) Summary: zeroequiv extremely slow (minor) Initial Comment: expr: LOG(x^2+SQRT(2)*x+1) -LOG(x^2-SQRT(2)*x+1) +2*ATAN((2*x+SQRT(2))/SQRT(2)) +2*ATAN((2*x-SQRT(2))/SQRT(2)) +SQRT(2)*LOG(x+1) -SQRT(2)*LOG(x-1) -2*SQRT(2)*ATAN(1/x)$ zeroequiv(expr,x) takes over a minute, though it is not at all subtle how non-zero it is: rectform(expr),numer, ..., x=0.1 => -3.31-4.44i ..., x=0.9 => 6.39-4.44i ..., x=1.1 => 7.38 ..., x=1.5 => 6.38 ..., x=20 => 6.28 Zeroequiv is really supposed to be quick and dirty.... ---------------------------------------------------------------------- >Comment By: Stavros Macrakis (macrakis) Date: 2009-01-17 16:49 Message: In Maxima 5.15, the original expression (but in lower case) takes 0.02 sec and correctly gives false. zeroequiv(LOG(1),x) correctly gives dontknow and returns instantaneously since Maxima function names are now lower-case (unlike in 2002 when the bug report was submitted). Closing as fixed. ---------------------------------------------------------------------- Comment By: Dieter Kaiser (crategus) Date: 2009-01-17 16:35 Message: This bug report is related to SF[593530] "Zeroequiv issues". zeroequiv is not used for in core functions. Problems are known and documented. This is the result for the example: (%i9) expr:LOG(x^2+SQRT(2)*x+1)-LOG(x^2-SQRT(2)*x+1)+2*ATAN((2*x+SQRT(2))/SQRT(2)) +2*ATAN((2*x-SQRT(2))/SQRT(2))+SQRT(2)*LOG(x+1) -SQRT(2)*LOG(x-1)-2*SQRT(2)*ATAN(1/x) (%i10) zeroequiv(expr,x); (%o10) dontknow On a Windows system with GCL 2.6.8 and a CPU with 1.8 GHZ we get (%i11) for i:1 thru 100000 do zeroequiv(expr,x); Evaluation took 15.8900 seconds (15.8900 elapsed) (%o11) done One call to zeroequiv needs about 16/100,000 seconds. Setting resolution to "wont fix" and status to pending. Dieter Kaiser ---------------------------------------------------------------------- You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=104933&aid=626760&group_id=4933 |