## [Maxima-bugs] [ maxima-Bugs-2787476 ] 'diff() inconsistent

 [Maxima-bugs] [ maxima-Bugs-2787476 ] 'diff() inconsistent From: SourceForge.net - 2009-11-29 02:20:13 ```Bugs item #2787476, was opened at 2009-05-05 19:41 Message generated for change (Comment added) made by sf-robot You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=104933&aid=2787476&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: Closed Resolution: Works For Me Priority: 5 Private: No Submitted By: iga Lenari (zigalenarcic) Assigned to: Nobody/Anonymous (nobody) Summary: 'diff() inconsistent Initial Comment: 'diff(x*y,x) gives the correct result (holds form), while 'diff(x,x) gives 1, calculates the differencial. ---------------------------------------------------------------------- >Comment By: SourceForge Robot (sf-robot) Date: 2009-11-29 02:20 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: 2009-11-14 23:37 Message: 'diff(x,x) gives 1 because of simplification in the simplifying function simpderiv. We have a similar simplification for integrals: (%i9) 'integrate(1,x); (%o9) x Therefore, we can do something like (%i10) 'diff('integrate(1,x),x); (%o10) 1 Furthermore, the following simplification is build in: (%i15) 'diff(x,x,0); (%o15) x This works for an arbitrary expression too: (%i17) 'diff(sin(x),x,0); (%o17) sin(x) It might be arguable why Maxima does not do more simplifications of this type, but the implement simplifications are not wrong. I have no example, where these simplifications cause problems. So, I would suggest not to change the behavior of Maxima to simplify the examples in this bug report. Setting the status to pending and resolution "works for me". Dieter Kaiser ---------------------------------------------------------------------- Comment By: iga Lenari (zigalenarcic) Date: 2009-05-13 13:26 Message: Problem is in quoted diff, which should not evaluate, but it does in 'diff(x,x) case: (%i2) 'diff(x*y,x); d (%o2) -- (x y) dx (%i3) 'diff(x,x); (%o3) 1 (%i4) 'diff(2*x,x); d (%o4) -- (2 x) dx ---------------------------------------------------------------------- Comment By: Nobody/Anonymous (nobody) Date: 2009-05-13 11:27 Message: I may be stupid or blind, but I do not see the problem here. Would you like to see diff(x*x,x) resulting in x rather than 2x? May be your remark is more subtle than this. ---------------------------------------------------------------------- You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=104933&aid=2787476&group_id=4933 ```

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 [Maxima-bugs] [ maxima-Bugs-2787476 ] 'diff() inconsistent From: SourceForge.net - 2009-05-05 19:41:16 ```Bugs item #2787476, was opened at 2009-05-05 21:41 Message generated for change (Tracker Item Submitted) made by zigalenarcic You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=104933&aid=2787476&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 Private: No Submitted By: Žiga Lenarčič (zigalenarcic) Assigned to: Nobody/Anonymous (nobody) Summary: 'diff() inconsistent Initial Comment: 'diff(x*y,x) gives the correct result (holds form), while 'diff(x,x) gives 1, calculates the differencial. ---------------------------------------------------------------------- You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=104933&aid=2787476&group_id=4933 ```
 [Maxima-bugs] [ maxima-Bugs-2787476 ] 'diff() inconsistent From: SourceForge.net - 2009-05-13 11:28:03 ```Bugs item #2787476, was opened at 2009-05-05 19:41 Message generated for change (Comment added) made by nobody You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=104933&aid=2787476&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 Private: No Submitted By: Žiga Lenarčič (zigalenarcic) Assigned to: Nobody/Anonymous (nobody) Summary: 'diff() inconsistent Initial Comment: 'diff(x*y,x) gives the correct result (holds form), while 'diff(x,x) gives 1, calculates the differencial. ---------------------------------------------------------------------- Comment By: Nobody/Anonymous (nobody) Date: 2009-05-13 11:27 Message: I may be stupid or blind, but I do not see the problem here. Would you like to see diff(x*x,x) resulting in x rather than 2x? May be your remark is more subtle than this. ---------------------------------------------------------------------- You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=104933&aid=2787476&group_id=4933 ```
 [Maxima-bugs] [ maxima-Bugs-2787476 ] 'diff() inconsistent From: SourceForge.net - 2009-05-13 13:26:26 ```Bugs item #2787476, was opened at 2009-05-05 21:41 Message generated for change (Comment added) made by zigalenarcic You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=104933&aid=2787476&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 Private: No Submitted By: Žiga Lenarčič (zigalenarcic) Assigned to: Nobody/Anonymous (nobody) Summary: 'diff() inconsistent Initial Comment: 'diff(x*y,x) gives the correct result (holds form), while 'diff(x,x) gives 1, calculates the differencial. ---------------------------------------------------------------------- >Comment By: Žiga Lenarčič (zigalenarcic) Date: 2009-05-13 15:26 Message: Problem is in quoted diff, which should not evaluate, but it does in 'diff(x,x) case: (%i2) 'diff(x*y,x); d (%o2) -- (x y) dx (%i3) 'diff(x,x); (%o3) 1 (%i4) 'diff(2*x,x); d (%o4) -- (2 x) dx ---------------------------------------------------------------------- Comment By: Nobody/Anonymous (nobody) Date: 2009-05-13 13:27 Message: I may be stupid or blind, but I do not see the problem here. Would you like to see diff(x*x,x) resulting in x rather than 2x? May be your remark is more subtle than this. ---------------------------------------------------------------------- You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=104933&aid=2787476&group_id=4933 ```
 [Maxima-bugs] [ maxima-Bugs-2787476 ] 'diff() inconsistent From: SourceForge.net - 2009-11-14 23:37:09 ```Bugs item #2787476, was opened at 2009-05-05 21:41 Message generated for change (Comment added) made by crategus You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=104933&aid=2787476&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: Pending >Resolution: Works For Me Priority: 5 Private: No Submitted By: Žiga Lenarčič (zigalenarcic) Assigned to: Nobody/Anonymous (nobody) Summary: 'diff() inconsistent Initial Comment: 'diff(x*y,x) gives the correct result (holds form), while 'diff(x,x) gives 1, calculates the differencial. ---------------------------------------------------------------------- >Comment By: Dieter Kaiser (crategus) Date: 2009-11-15 00:37 Message: 'diff(x,x) gives 1 because of simplification in the simplifying function simpderiv. We have a similar simplification for integrals: (%i9) 'integrate(1,x); (%o9) x Therefore, we can do something like (%i10) 'diff('integrate(1,x),x); (%o10) 1 Furthermore, the following simplification is build in: (%i15) 'diff(x,x,0); (%o15) x This works for an arbitrary expression too: (%i17) 'diff(sin(x),x,0); (%o17) sin(x) It might be arguable why Maxima does not do more simplifications of this type, but the implement simplifications are not wrong. I have no example, where these simplifications cause problems. So, I would suggest not to change the behavior of Maxima to simplify the examples in this bug report. Setting the status to pending and resolution "works for me". Dieter Kaiser ---------------------------------------------------------------------- Comment By: Žiga Lenarčič (zigalenarcic) Date: 2009-05-13 15:26 Message: Problem is in quoted diff, which should not evaluate, but it does in 'diff(x,x) case: (%i2) 'diff(x*y,x); d (%o2) -- (x y) dx (%i3) 'diff(x,x); (%o3) 1 (%i4) 'diff(2*x,x); d (%o4) -- (2 x) dx ---------------------------------------------------------------------- Comment By: Nobody/Anonymous (nobody) Date: 2009-05-13 13:27 Message: I may be stupid or blind, but I do not see the problem here. Would you like to see diff(x*x,x) resulting in x rather than 2x? May be your remark is more subtle than this. ---------------------------------------------------------------------- You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=104933&aid=2787476&group_id=4933 ```
 [Maxima-bugs] [ maxima-Bugs-2787476 ] 'diff() inconsistent From: SourceForge.net - 2009-11-29 02:20:13 ```Bugs item #2787476, was opened at 2009-05-05 19:41 Message generated for change (Comment added) made by sf-robot You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=104933&aid=2787476&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: Closed Resolution: Works For Me Priority: 5 Private: No Submitted By: iga Lenari (zigalenarcic) Assigned to: Nobody/Anonymous (nobody) Summary: 'diff() inconsistent Initial Comment: 'diff(x*y,x) gives the correct result (holds form), while 'diff(x,x) gives 1, calculates the differencial. ---------------------------------------------------------------------- >Comment By: SourceForge Robot (sf-robot) Date: 2009-11-29 02:20 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: 2009-11-14 23:37 Message: 'diff(x,x) gives 1 because of simplification in the simplifying function simpderiv. We have a similar simplification for integrals: (%i9) 'integrate(1,x); (%o9) x Therefore, we can do something like (%i10) 'diff('integrate(1,x),x); (%o10) 1 Furthermore, the following simplification is build in: (%i15) 'diff(x,x,0); (%o15) x This works for an arbitrary expression too: (%i17) 'diff(sin(x),x,0); (%o17) sin(x) It might be arguable why Maxima does not do more simplifications of this type, but the implement simplifications are not wrong. I have no example, where these simplifications cause problems. So, I would suggest not to change the behavior of Maxima to simplify the examples in this bug report. Setting the status to pending and resolution "works for me". Dieter Kaiser ---------------------------------------------------------------------- Comment By: iga Lenari (zigalenarcic) Date: 2009-05-13 13:26 Message: Problem is in quoted diff, which should not evaluate, but it does in 'diff(x,x) case: (%i2) 'diff(x*y,x); d (%o2) -- (x y) dx (%i3) 'diff(x,x); (%o3) 1 (%i4) 'diff(2*x,x); d (%o4) -- (2 x) dx ---------------------------------------------------------------------- Comment By: Nobody/Anonymous (nobody) Date: 2009-05-13 11:27 Message: I may be stupid or blind, but I do not see the problem here. Would you like to see diff(x*x,x) resulting in x rather than 2x? May be your remark is more subtle than this. ---------------------------------------------------------------------- You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=104933&aid=2787476&group_id=4933 ```