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omorr		#1 Posted : 25 June 2012 11:17:37(UTC)
Rank: Administration Groups: Registered, Advanced Member Joined: 23/06/2009(UTC) Posts: 1,740 Was thanked: 318 time(s) in 268 post(s)		Hello, Look at this please f:el(x,1)^3+el(x,2)^3 This is correct: diff(diff(f,el(x,1)),el(x,2))=0 But this is obviously wrong: v0.95 diff(diff(f,el(x,2)),el(x,1))=-el(x,2)*(-1+el(x,2)) It seems that is still present in v.90 as well: v0.90 diff(diff(f,el(x,2)),el(x,1))—-(-1+el(x,2))*el(x,2) In v0.89.8 you will get the right answer - zeros for both mixed derivatives. Regards, Radovan Edited by user 25 June 2012 11:21:40(UTC)  | Reason: Not specified
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omorr		#2 Posted : 30 July 2012 10:14:57(UTC)
Rank: Administration Groups: Registered, Advanced Member Joined: 23/06/2009(UTC) Posts: 1,740 Was thanked: 318 time(s) in 268 post(s)		Hello, This is still present in 0.95 build 4594 (30 July 2012). Any comments? Regards, Radovan
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Davide Carpi		#3 Posted : 31 July 2012 01:59:59(UTC)
Rank: Advanced Member Groups: Registered, Advanced Member Joined: 13/01/2012(UTC) Posts: 2,647 Location: Italy Was thanked: 1329 time(s) in 875 post(s)		Hi omorr, Originally Posted by: omorr Hello, This is still present in 0.95 build 4594 (30 July 2012). Any comments? Regards, Radovan I confirm! seem related to the symbolic simplification (see the attachments) regards, w3b5urf3r Edited by user 31 July 2012 02:03:47(UTC)  | Reason: Not specified File Attachment(s): derivatives_debug.sm (37kb) downloaded 29 time(s). Davide Carpi attached the following image(s):
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1 user thanked Davide Carpi for this useful post.		on 31/07/2012(UTC)
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Davide Carpi		#4 Posted : 09 October 2012 02:26:09(UTC)
Rank: Advanced Member Groups: Registered, Advanced Member Joined: 13/01/2012(UTC) Posts: 2,647 Location: Italy Was thanked: 1329 time(s) in 875 post(s)		Here some (probably) related issues. best regards, w3b5urf3r
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ElSid		#5 Posted : 10 October 2012 23:33:54(UTC)
Rank: Advanced Member Groups: Registered Joined: 05/03/2009(UTC) Posts: 433 Location: USA Was thanked: 17 time(s) in 15 post(s)		It's the way SMath handles/prioritizes ASCII characters. I ran into a similar issue with MathCAD. In this case, the second variable of "x" (in the equation) has to be the first variable of the first derivative as shown in w3b5urf3r's screen shot.
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omorr		#6 Posted : 03 May 2013 23:11:41(UTC)
Rank: Administration Groups: Registered, Advanced Member Joined: 23/06/2009(UTC) Posts: 1,740 Was thanked: 318 time(s) in 268 post(s)		Hello, I must be boring with this , but I think there is neither solution nor satisfactory explanation of this "glitch" regarding second derivatives. Still present in 0.96 Regards, Radovan omorr attached the following image(s):
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uni		#7 Posted : 03 May 2013 23:23:02(UTC)
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omorr		#8 Posted : 03 May 2013 23:32:12(UTC)
Rank: Administration Groups: Registered, Advanced Member Joined: 23/06/2009(UTC) Posts: 1,740 Was thanked: 318 time(s) in 268 post(s)		Originally Posted by: uni Yes, I know. Thank you . I did it on purpose, just to put the stress that maple did it right. Regards, Radovan
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