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From: SourceForge.net <noreply@so...>  20110405 17:41:02

Bugs item #3276461, was opened at 20110406 00:41 Message generated for change (Tracker Item Submitted) made by bonoxofut You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=104933&aid=3276461&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  Limit Group: None Status: Open Resolution: None Priority: 5 Private: No Submitted By: eEniquEe (bonoxofut) Assigned to: Nobody/Anonymous (nobody) Summary: Inaccurate Limit Evaluation Initial Comment: Hi, While working on my project on Limit Problem Generation, I've encountered a bug. The following limit is evaluated incorrectly!!! (%i1) limit((4*x^210*x+24)/((4*x+8)^(1/3)+2), x, 4); (%o1) 0 The result should be 66 instead. It's pretty strange, because Maxima can evaluate another limit of the same type correctly: (%i2) limit((2*x^215*x25)/((4*x21)^(1/3)+1), x, 5); (%o2) 15/4 tlimit returns the correct value as expected. I just wondered what was wrong with limit function. :( Thanks guys very much for all your efforts to maintain Maxima, Keep up the good work, And have a great day, :)  You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=104933&aid=3276461&group_id=4933 
From: SourceForge.net <noreply@so...>  20110407 17:35:33

Bugs item #3276461, was opened at 20110406 00:41 Message generated for change (Comment added) made by bonoxofut You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=104933&aid=3276461&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  Limit Group: None Status: Open Resolution: None Priority: 5 Private: No Submitted By: eEniquEe (bonoxofut) Assigned to: Nobody/Anonymous (nobody) Summary: Inaccurate Limit Evaluation Initial Comment: Hi, While working on my project on Limit Problem Generation, I've encountered a bug. The following limit is evaluated incorrectly!!! (%i1) limit((4*x^210*x+24)/((4*x+8)^(1/3)+2), x, 4); (%o1) 0 The result should be 66 instead. It's pretty strange, because Maxima can evaluate another limit of the same type correctly: (%i2) limit((2*x^215*x25)/((4*x21)^(1/3)+1), x, 5); (%o2) 15/4 tlimit returns the correct value as expected. I just wondered what was wrong with limit function. :( Thanks guys very much for all your efforts to maintain Maxima, Keep up the good work, And have a great day, :)  >Comment By: eEniquEe (bonoxofut) Date: 20110408 00:35 Message: Hi again, It appears that in some specific cases, limit.lisp seems to act weirdly. I don't know why, but it appears that Maxima fails to evaluate this limit: (%i1) limit((16*x^3+16*x^232*x32)/(16*x^320*x^2+32*x+40), x, sqrt(2)) (%o1) (15569*2^(5/2)88072)/(68725*sqrt(2)97192) The result given by tlimit is even more monstrous: (%i2) tlimit((16*x^3+16*x^232*x32)/(16*x^320*x^2+32*x+40), x, sqrt(2)); (%o2) (28587895628423267593*2^(5/2)161717558869690800084)/(7887067287668281425*2^(9/2)178463960409114635249) The result should be: (16*sqrt(2)+16)/(16*sqrt(2)20) instead. The 2 expressions (the correct result, and the result given by limit function) are pretty much identical when we take the float value of it. But however, in fact, they are not the same!!! The above limit can be easily found either by L'Hopital's Rule, or by factoring out (x^2  2), which makes both numerator and denominator tend to 0.  I'm not very familiar with programming, (well, in fact, I do have some basic programming, scripting skill, I can create small applicants: small games, and auto stuff), but I really want to help you guys in modifying the limit.lisp. I don't really know how. :( I just wanna ask, if I w ant to modify the Lisp(s) in Maxima, which programming language should I consider? Thanks very much in advance, :)  You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=104933&aid=3276461&group_id=4933 
From: SourceForge.net <noreply@so...>  20111012 18:59:31

Bugs item #3276461, was opened at 20110405 13:41 Message generated for change (Comment added) made by dgildea You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=104933&aid=3276461&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  Limit Group: None >Status: Closed >Resolution: Fixed Priority: 5 Private: No Submitted By: eEniquEe (bonoxofut) >Assigned to: Dan Gildea (dgildea) Summary: Inaccurate Limit Evaluation Initial Comment: Hi, While working on my project on Limit Problem Generation, I've encountered a bug. The following limit is evaluated incorrectly!!! (%i1) limit((4*x^210*x+24)/((4*x+8)^(1/3)+2), x, 4); (%o1) 0 The result should be 66 instead. It's pretty strange, because Maxima can evaluate another limit of the same type correctly: (%i2) limit((2*x^215*x25)/((4*x21)^(1/3)+1), x, 5); (%o2) 15/4 tlimit returns the correct value as expected. I just wondered what was wrong with limit function. :( Thanks guys very much for all your efforts to maintain Maxima, Keep up the good work, And have a great day, :)  >Comment By: Dan Gildea (dgildea) Date: 20111012 14:59 Message: Fixed in limit.lisp  add radcan before zero check in simplimsubst.  Comment By: eEniquEe (bonoxofut) Date: 20110407 13:35 Message: Hi again, It appears that in some specific cases, limit.lisp seems to act weirdly. I don't know why, but it appears that Maxima fails to evaluate this limit: (%i1) limit((16*x^3+16*x^232*x32)/(16*x^320*x^2+32*x+40), x, sqrt(2)) (%o1) (15569*2^(5/2)88072)/(68725*sqrt(2)97192) The result given by tlimit is even more monstrous: (%i2) tlimit((16*x^3+16*x^232*x32)/(16*x^320*x^2+32*x+40), x, sqrt(2)); (%o2) (28587895628423267593*2^(5/2)161717558869690800084)/(7887067287668281425*2^(9/2)178463960409114635249) The result should be: (16*sqrt(2)+16)/(16*sqrt(2)20) instead. The 2 expressions (the correct result, and the result given by limit function) are pretty much identical when we take the float value of it. But however, in fact, they are not the same!!! The above limit can be easily found either by L'Hopital's Rule, or by factoring out (x^2  2), which makes both numerator and denominator tend to 0.  I'm not very familiar with programming, (well, in fact, I do have some basic programming, scripting skill, I can create small applicants: small games, and auto stuff), but I really want to help you guys in modifying the limit.lisp. I don't really know how. :( I just wanna ask, if I w ant to modify the Lisp(s) in Maxima, which programming language should I consider? Thanks very much in advance, :)  You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=104933&aid=3276461&group_id=4933 