From: SourceForge.net <no...@so...> - 2006-01-30 20:31:25
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Bugs item #1419046, was opened at 2006-01-30 14:31 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=1419046&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: None Group: None Status: Open Resolution: None Priority: 5 Submitted By: Barton Willis (willisbl) Assigned to: Nobody/Anonymous (nobody) Summary: sign bug Initial Comment: (%i14) 1-sqrt(1-x); (%o14) 1-sqrt(1-x) (%i15) x * diff(%,x)/%; (%o15) x/(2*(1-sqrt(1-x))*sqrt(1-x)) (%i16) abs(%); Yeechs! numerator is x. (%o16) x/(2*abs(sqrt(1-x)-1)*sqrt(1-x)) Let's check the sign at -0.1 (%i17) subst(x=-0.1,%); (%o17) -0.97673129462279451 Try again using cabs; this looks OK: (%i18) 1-sqrt(1-x); (%o18) 1-sqrt(1-x) (%i19) x * diff(%,x)/%; (%o19) x/(2*(1-sqrt(1-x))*sqrt(1-x)) (%i20) cabs(%); Is x - 1 positive, negative, or zero? neg; (%o20) abs(x)/abs(2*x+2*sqrt(1-x)-2) Let's try again -- this time I'll trace sign (%i23) x * diff(%,x)/%; (%o23) x/(2*(1-sqrt(1-x))*sqrt(1-x)) (%i24) abs(%); 1 Enter sign [x/(2*(1-sqrt(1-x))*sqrt(1-x))] 1 Exit sign pn 1 Enter sign [1/(1-sqrt(1-x))] 1 Exit sign pn 1 Enter sign [1-sqrt(1-x)] 1 Exit sign pn 1 Enter sign [1/sqrt(1-x)] 1 Exit sign pos 1 Enter sign [x] 1 Exit sign pos <--- bogus (%i30) build_info(); Maxima version: 5.9.2.19cvs Maxima build date: 10:34 1/27/2006 host type: i686-pc-mingw32 lisp-implementation-type: GNU Common Lisp (GCL) lisp-implementation-version: GCL 2.6.7 Barton ---------------------------------------------------------------------- You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=104933&aid=1419046&group_id=4933 |
From: SourceForge.net <no...@so...> - 2006-08-15 03:11:25
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Bugs item #1419046, was opened at 2006-01-30 13:31 Message generated for change (Comment added) made by robert_dodier You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=104933&aid=1419046&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: Open Resolution: None Priority: 5 Submitted By: Barton Willis (willisbl) Assigned to: Nobody/Anonymous (nobody) Summary: sign bug Initial Comment: (%i14) 1-sqrt(1-x); (%o14) 1-sqrt(1-x) (%i15) x * diff(%,x)/%; (%o15) x/(2*(1-sqrt(1-x))*sqrt(1-x)) (%i16) abs(%); Yeechs! numerator is x. (%o16) x/(2*abs(sqrt(1-x)-1)*sqrt(1-x)) Let's check the sign at -0.1 (%i17) subst(x=-0.1,%); (%o17) -0.97673129462279451 Try again using cabs; this looks OK: (%i18) 1-sqrt(1-x); (%o18) 1-sqrt(1-x) (%i19) x * diff(%,x)/%; (%o19) x/(2*(1-sqrt(1-x))*sqrt(1-x)) (%i20) cabs(%); Is x - 1 positive, negative, or zero? neg; (%o20) abs(x)/abs(2*x+2*sqrt(1-x)-2) Let's try again -- this time I'll trace sign (%i23) x * diff(%,x)/%; (%o23) x/(2*(1-sqrt(1-x))*sqrt(1-x)) (%i24) abs(%); 1 Enter sign [x/(2*(1-sqrt(1-x))*sqrt(1-x))] 1 Exit sign pn 1 Enter sign [1/(1-sqrt(1-x))] 1 Exit sign pn 1 Enter sign [1-sqrt(1-x)] 1 Exit sign pn 1 Enter sign [1/sqrt(1-x)] 1 Exit sign pos 1 Enter sign [x] 1 Exit sign pos <--- bogus (%i30) build_info(); Maxima version: 5.9.2.19cvs Maxima build date: 10:34 1/27/2006 host type: i686-pc-mingw32 lisp-implementation-type: GNU Common Lisp (GCL) lisp-implementation-version: GCL 2.6.7 Barton ---------------------------------------------------------------------- >Comment By: Robert Dodier (robert_dodier) Date: 2006-08-14 21:11 Message: Logged In: YES user_id=501686 Observed in 5.9.3.99rc1 / Clisp 2.38. ---------------------------------------------------------------------- You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=104933&aid=1419046&group_id=4933 |
From: SourceForge.net <no...@so...> - 2009-03-15 21:22:37
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Bugs item #1419046, was opened at 2006-01-30 15:31 Message generated for change (Comment added) made by dgildea You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=104933&aid=1419046&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: Fixed Priority: 5 Private: No Submitted By: Barton Willis (willisbl) >Assigned to: Dan Gildea (dgildea) Summary: sign bug Initial Comment: (%i14) 1-sqrt(1-x); (%o14) 1-sqrt(1-x) (%i15) x * diff(%,x)/%; (%o15) x/(2*(1-sqrt(1-x))*sqrt(1-x)) (%i16) abs(%); Yeechs! numerator is x. (%o16) x/(2*abs(sqrt(1-x)-1)*sqrt(1-x)) Let's check the sign at -0.1 (%i17) subst(x=-0.1,%); (%o17) -0.97673129462279451 Try again using cabs; this looks OK: (%i18) 1-sqrt(1-x); (%o18) 1-sqrt(1-x) (%i19) x * diff(%,x)/%; (%o19) x/(2*(1-sqrt(1-x))*sqrt(1-x)) (%i20) cabs(%); Is x - 1 positive, negative, or zero? neg; (%o20) abs(x)/abs(2*x+2*sqrt(1-x)-2) Let's try again -- this time I'll trace sign (%i23) x * diff(%,x)/%; (%o23) x/(2*(1-sqrt(1-x))*sqrt(1-x)) (%i24) abs(%); 1 Enter sign [x/(2*(1-sqrt(1-x))*sqrt(1-x))] 1 Exit sign pn 1 Enter sign [1/(1-sqrt(1-x))] 1 Exit sign pn 1 Enter sign [1-sqrt(1-x)] 1 Exit sign pn 1 Enter sign [1/sqrt(1-x)] 1 Exit sign pos 1 Enter sign [x] 1 Exit sign pos <--- bogus (%i30) build_info(); Maxima version: 5.9.2.19cvs Maxima build date: 10:34 1/27/2006 host type: i686-pc-mingw32 lisp-implementation-type: GNU Common Lisp (GCL) lisp-implementation-version: GCL 2.6.7 Barton ---------------------------------------------------------------------- >Comment By: Dan Gildea (dgildea) Date: 2009-03-15 17:21 Message: Fixed in compar.lisp rev 1.46. (%i1) 1-sqrt(1-x); (%o1) 1-sqrt(1-x) (%i2) x * diff(%,x)/%; (%o2) x/(2*(1-sqrt(1-x))*sqrt(1-x)) (%i3) abs(%); (%o3) abs(x)/(2*abs(sqrt(1-x)-1)*sqrt(1-x)) ---------------------------------------------------------------------- Comment By: Robert Dodier (robert_dodier) Date: 2006-08-14 23:11 Message: Logged In: YES user_id=501686 Observed in 5.9.3.99rc1 / Clisp 2.38. ---------------------------------------------------------------------- You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=104933&aid=1419046&group_id=4933 |