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From: SourceForge.net <noreply@so...>  20110422 21:46:43

Bugs item #1318843, was opened at 20051008 22:52 Message generated for change (Comment added) made by crategus You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=104933&aid=1318843&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  Assume Group: None >Status: Pending >Resolution: Works For Me Priority: 5 Private: No Submitted By: Robert Dodier (robert_dodier) Assigned to: Nobody/Anonymous (nobody) Summary: assume failure to deduce, and consequent infinite looping Initial Comment: assume (a > 0, b > 0, c > 0, d > 0); assume (c*s + d < 0); assume (equal (c*r + d, 0)); At this point, r = d/c and s < d/c, so s < r. However, integrate ((a*x+b)/(c*x+d), x, r, s); => Is s  r positive, negative, or zero? response: n; => a solution response: p; or z; => somebody calls ASKSIGN1 over and over 1> (ASKSIGN1 ((MPLUS SIMP) ((MTIMES SIMP RATSIMP) 1 $D) ((MTIMES SIMP RATSIMP) 1 $C $R))) <1 (ASKSIGN1 $ZERO) 1> (ASKSIGN1 ((MPLUS SIMP) $D ((MTIMES SIMP RATSIMP) $C $R))) <1 (ASKSIGN1 $ZERO) 1> (ASKSIGN1 ((MPLUS SIMP) ((MTIMES SIMP RATSIMP) 1 $D) ((MTIMES SIMP RATSIMP) 1 $C $R))) <1 (ASKSIGN1 $ZERO) 1> (ASKSIGN1 ((MPLUS SIMP) $D ((MTIMES SIMP RATSIMP) $C $R))) <1 (ASKSIGN1 $ZERO) etc etc indefinitely. There are at least 2 problems here. (1) ASKSIGN failed to determine that s < r and therefore there is no need for asking about it. (2) If the response implies something inconsistent with the facts assumed thus far, something (maybe ASKSIGN) goes nuts. I'm inclined to think (2) is more serious. Whatever the limitations of the assume mechanism to derive stuff from facts, it shouldn't freak out under any circumstances. Problem verified in 5.9.0 on Allegro CL 6.2, and 5.9.1.9rc4 on GCL 2.6.7.  >Comment By: Dieter Kaiser (crategus) Date: 20110422 23:46 Message: The problem of infinite looping is no longer present with Maxima 5.24post: (%i1) assume (a > 0, b > 0, c > 0, d > 0)$ (%i2) assume (c*s + d < 0)$ (%i3) assume (equal (c*r + d, 0))$ (%i4) integrate ((a*x+b)/(c*x+d), x, r, s); Is sr positive, negative, or zero? p; (%o4) a*d*log(abs(c*x+c*r+d))/c^2b*log(abs(c*x+c*r+d))/ca*x/c ((a*db*c)*log(c*sd)a*c*s)/c^2a*r/c (%i5) integrate ((a*x+b)/(c*x+d), x, r, s); Is sr positive, negative, or zero? z; (%o5) a*d*log(abs(c*x+c*r+d))/c^2b*log(abs(c*x+c*r+d))/ca*x/c ((a*db*c)*log(c*sd)a*c*s)/c^2a*r/c (%i6) integrate ((a*x+b)/(c*x+d), x, r, s); Is sr positive, negative, or zero? n; Principal Value (%o6) a*d*log(c*s+d)/c^2b*log(c*s+d)/ca*s/ca*d*log(c*r+d)/c^2 +b*log(c*r+d)/c+a*r/clog(1)*a*d/c^2+log(1)*b/c Still there is the problem, that the assume database is too weak to determine the sign of sr. Nevertheless, at this point I would like to suggest to close this bug report as "works for me". Dieter Kaiser  You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=104933&aid=1318843&group_id=4933 
From: SourceForge.net <noreply@so...>  20110506 22:20:05

Bugs item #1318843, was opened at 20051008 20:52 Message generated for change (Settings changed) made by sfrobot You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=104933&aid=1318843&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  Assume Group: None >Status: Closed Resolution: Works For Me Priority: 5 Private: No Submitted By: Robert Dodier (robert_dodier) Assigned to: Nobody/Anonymous (nobody) Summary: assume failure to deduce, and consequent infinite looping Initial Comment: assume (a > 0, b > 0, c > 0, d > 0); assume (c*s + d < 0); assume (equal (c*r + d, 0)); At this point, r = d/c and s < d/c, so s < r. However, integrate ((a*x+b)/(c*x+d), x, r, s); => Is s  r positive, negative, or zero? response: n; => a solution response: p; or z; => somebody calls ASKSIGN1 over and over 1> (ASKSIGN1 ((MPLUS SIMP) ((MTIMES SIMP RATSIMP) 1 $D) ((MTIMES SIMP RATSIMP) 1 $C $R))) <1 (ASKSIGN1 $ZERO) 1> (ASKSIGN1 ((MPLUS SIMP) $D ((MTIMES SIMP RATSIMP) $C $R))) <1 (ASKSIGN1 $ZERO) 1> (ASKSIGN1 ((MPLUS SIMP) ((MTIMES SIMP RATSIMP) 1 $D) ((MTIMES SIMP RATSIMP) 1 $C $R))) <1 (ASKSIGN1 $ZERO) 1> (ASKSIGN1 ((MPLUS SIMP) $D ((MTIMES SIMP RATSIMP) $C $R))) <1 (ASKSIGN1 $ZERO) etc etc indefinitely. There are at least 2 problems here. (1) ASKSIGN failed to determine that s < r and therefore there is no need for asking about it. (2) If the response implies something inconsistent with the facts assumed thus far, something (maybe ASKSIGN) goes nuts. I'm inclined to think (2) is more serious. Whatever the limitations of the assume mechanism to derive stuff from facts, it shouldn't freak out under any circumstances. Problem verified in 5.9.0 on Allegro CL 6.2, and 5.9.1.9rc4 on GCL 2.6.7.  >Comment By: SourceForge Robot (sfrobot) Date: 20110506 22:20 Message: This Tracker item was closed automatically by the system. It was previously set to a Pending status, and the original submitter did not respond within 14 days (the time period specified by the administrator of this Tracker).  Comment By: Dieter Kaiser (crategus) Date: 20110422 21:46 Message: The problem of infinite looping is no longer present with Maxima 5.24post: (%i1) assume (a > 0, b > 0, c > 0, d > 0)$ (%i2) assume (c*s + d < 0)$ (%i3) assume (equal (c*r + d, 0))$ (%i4) integrate ((a*x+b)/(c*x+d), x, r, s); Is sr positive, negative, or zero? p; (%o4) a*d*log(abs(c*x+c*r+d))/c^2b*log(abs(c*x+c*r+d))/ca*x/c ((a*db*c)*log(c*sd)a*c*s)/c^2a*r/c (%i5) integrate ((a*x+b)/(c*x+d), x, r, s); Is sr positive, negative, or zero? z; (%o5) a*d*log(abs(c*x+c*r+d))/c^2b*log(abs(c*x+c*r+d))/ca*x/c ((a*db*c)*log(c*sd)a*c*s)/c^2a*r/c (%i6) integrate ((a*x+b)/(c*x+d), x, r, s); Is sr positive, negative, or zero? n; Principal Value (%o6) a*d*log(c*s+d)/c^2b*log(c*s+d)/ca*s/ca*d*log(c*r+d)/c^2 +b*log(c*r+d)/c+a*r/clog(1)*a*d/c^2+log(1)*b/c Still there is the problem, that the assume database is too weak to determine the sign of sr. Nevertheless, at this point I would like to suggest to close this bug report as "works for me". Dieter Kaiser  You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=104933&aid=1318843&group_id=4933 