From: SourceForge.net <noreply@so...>  20030924 04:13:17

Bugs item #811522, was opened at 20030924 00:13 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=811522&group_id=4933 Category: None Group: None Status: Open Resolution: None Priority: 5 Submitted By: Stavros Macrakis (macrakis) Assigned to: Nobody/Anonymous (nobody) Summary: redundant question in limit Initial Comment: limit(r^(b2)*(xr)^2,r,0) Is b  2 positive, negative, or zero? neg; Is x zero or nonzero? zero; Is b an integer? yes; Is 2  b an even number? no; Is 2  b an even number? <== redundant question no;  You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=104933&aid=811522&group_id=4933 
From: SourceForge.net <noreply@so...>  20060409 20:39:13

Bugs item #811522, was opened at 20030923 22:13 Message generated for change (Settings changed) made by robert_dodier You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=104933&aid=811522&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: Stavros Macrakis (macrakis) Assigned to: Nobody/Anonymous (nobody) Summary: redundant question in limit Initial Comment: limit(r^(b2)*(xr)^2,r,0) Is b  2 positive, negative, or zero? neg; Is x zero or nonzero? zero; Is b an integer? yes; Is 2  b an even number? no; Is 2  b an even number? <== redundant question no;  You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=104933&aid=811522&group_id=4933 
From: SourceForge.net <noreply@so...>  20100314 01:03:13

Bugs item #811522, was opened at 20030924 06:13 Message generated for change (Comment added) made by crategus You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=104933&aid=811522&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 Private: No Submitted By: Stavros Macrakis (macrakis) Assigned to: Nobody/Anonymous (nobody) Summary: redundant question in limit Initial Comment: limit(r^(b2)*(xr)^2,r,0) Is b  2 positive, negative, or zero? neg; Is x zero or nonzero? zero; Is b an integer? yes; Is 2  b an even number? no; Is 2  b an even number? <== redundant question no;  >Comment By: Dieter Kaiser (crategus) Date: 20100314 02:03 Message: At first again the example of this bug report with the current Maxima 5.20post: (%i2) limit(r^(b2)*(xr)^2,r,0); Is b2 positive, negative, or zero? n; Is b positive, negative, or zero? z; Is 2b an even number? n; Is 2b an even number? n; Is 2b an even number? n; (%o2) 'limit(r^(b2)*(xr)^2,r,0) After the second question Maxima knows that b=0. Therefore, the expression 2b is even. But Maxima does not recognize this. The answer is in contradiction to the known facts and Maxima asks the same question three times. The reason is that the function evod which is called from askinteger does not look into the database for facts like equal(b,0). We had the same problem with maximaintegerp and introduced the extension checkintegerfacts. We can extend the routine checkintegerfacts to look for facts which are related to even or odd integers. With such an extension we will get: (%i4) limit(r^(b2)*(xr)^2,r,0); Is b2 positive, negative, or zero? n; Is b positive, negative, or zero? z; (%o4) 'limit(r^(b2)*(xr)^2,r,0) Maxima no longer ask the quesition "Is 2b an even number?" because this fact is deduced from the database. This is another simple example. We assume n equal to 2. Therefore n is even, but Maxima does not know it: (%i1) assume(equal(n,2))$ (%i3) askinteger(n,even); Is n an even number? y; With the extension of checkintegerfacts we get: (%i5) assume(equal(n,2))$ (%i6) assume(equal(m,3))$ (%i7) askinteger(n,even); (%o7) yes (%i8) askinteger(m,odd); (%o8) yes Dieter Kaiser  You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=104933&aid=811522&group_id=4933 
From: SourceForge.net <noreply@so...>  20100320 20:20:12

Bugs item #811522, was opened at 20030924 06:13 Message generated for change (Comment added) made by crategus You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=104933&aid=811522&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: Stavros Macrakis (macrakis) Assigned to: Nobody/Anonymous (nobody) Summary: redundant question in limit Initial Comment: limit(r^(b2)*(xr)^2,r,0) Is b  2 positive, negative, or zero? neg; Is x zero or nonzero? zero; Is b an integer? yes; Is 2  b an even number? no; Is 2  b an even number? <== redundant question no;  >Comment By: Dieter Kaiser (crategus) Date: 20100320 21:20 Message: Fixed in compar.lisp revision 1.69. We no longer get the redundant questions: (%i3) limit(r^(b2)*(xr)^2,r,0); Is b2 positive, negative, or zero? n; Is b positive, negative, or zero? z; (%o3) 'limit(r^(b2)*(xr)^2,r,0) Closing this bug report as fixed. Dieter Kaiser  Comment By: Dieter Kaiser (crategus) Date: 20100314 02:03 Message: At first again the example of this bug report with the current Maxima 5.20post: (%i2) limit(r^(b2)*(xr)^2,r,0); Is b2 positive, negative, or zero? n; Is b positive, negative, or zero? z; Is 2b an even number? n; Is 2b an even number? n; Is 2b an even number? n; (%o2) 'limit(r^(b2)*(xr)^2,r,0) After the second question Maxima knows that b=0. Therefore, the expression 2b is even. But Maxima does not recognize this. The answer is in contradiction to the known facts and Maxima asks the same question three times. The reason is that the function evod which is called from askinteger does not look into the database for facts like equal(b,0). We had the same problem with maximaintegerp and introduced the extension checkintegerfacts. We can extend the routine checkintegerfacts to look for facts which are related to even or odd integers. With such an extension we will get: (%i4) limit(r^(b2)*(xr)^2,r,0); Is b2 positive, negative, or zero? n; Is b positive, negative, or zero? z; (%o4) 'limit(r^(b2)*(xr)^2,r,0) Maxima no longer ask the quesition "Is 2b an even number?" because this fact is deduced from the database. This is another simple example. We assume n equal to 2. Therefore n is even, but Maxima does not know it: (%i1) assume(equal(n,2))$ (%i3) askinteger(n,even); Is n an even number? y; With the extension of checkintegerfacts we get: (%i5) assume(equal(n,2))$ (%i6) assume(equal(m,3))$ (%i7) askinteger(n,even); (%o7) yes (%i8) askinteger(m,odd); (%o8) yes Dieter Kaiser  You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=104933&aid=811522&group_id=4933 