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Offline tomtit  
#1 Posted : 07 October 2019 19:03:02(UTC)
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Please see attached example.
sym_diff_issue.sm (4kb) downloaded 19 time(s).
Offline Jean Giraud  
#2 Posted : 08 October 2019 03:49:29(UTC)
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Originally Posted by: tomtit Go to Quoted Post
Please see attached example.

What about completing the code to make it profitable ?
Not new the derivative of a constant is 0.

Derivative.PNG
Offline Razonar  
#3 Posted : 08 October 2019 04:07:31(UTC)
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Hi Tom. maple() knows how to eval diff because, as plugin, Viacheslav (uni, plugin author) know how to handle the function el(A,k). But notice what happen with an unknoun function, like El(A,k). So, problem here is what to do with the SMath el(A,k) with the operator diff.

Clipboard02.gif

Best regards.
Alvaro.
thanks 1 user thanked Razonar for this useful post.
on 08/10/2019(UTC)
Offline Jean Giraud  
#4 Posted : 08 October 2019 12:14:03(UTC)
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Get more from the companions ...

maple D(n).PNG
Offline Jean Giraud  
#5 Posted : 08 October 2019 15:34:26(UTC)
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Originally Posted by: Razonar Go to Quoted Post
Hi Tom. maple() knows how to eval diff because, as plugin, Viacheslav (uni, plugin author) know how to handle the function el(A,k). But notice what happen with an unknoun function, like El(A,k). So, problem here is what to do with the SMath el(A,k) with the operator diff.

As you mentioned Ei(x), like many special functions,
you may have to rescue from infinitesimal analysis,
the ancestor of CAS.

sym_diff_issue (more).sm (13kb) downloaded 7 time(s).
Offline tomtit  
#6 Posted : 08 October 2019 17:35:59(UTC)
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I think this is a bug.
If there is no evidence that variable A[k] depends on x, dA[k]/dx should be immediately set to 0.
This is the way how symbolic engine of Wolfram Mathematica works.
Probably, I made a mistake mentioning "indexed functions", the right subject name should be "indexed symbolic variables" instead.
In real case A[k] were indexed unknowns in the system of equations.
I intentionally made this example as simple as possible to make it evident.

Edited by user 08 October 2019 17:38:45(UTC)  | Reason: Not specified

Offline Jean Giraud  
#7 Posted : 08 October 2019 21:52:05(UTC)
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Originally Posted by: tomtit Go to Quoted Post
In real case A[k] were indexed unknowns in the system of equations.
I intentionally made this example as simple as possible to make it evident.

You can do lot more from lot less for real project:
1. get your function from index
2. get the partial derivatives wrt parameters in function.

sym_diff_issue (more).sm (24kb) downloaded 13 time(s).
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