Seems, like I faced 2 bugs simultaneously... From four (almost) equivalent expressions only one is calculated correctly.

1. Wrong derivative atan() with 2 arguments, shown in red.

2. Two expressions are shown in yellow, where error is reported, although the same term with dot products is successfully calculated in another expression (shown in green).

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You seem familiar with Maple.

Can't help in there, Mathcad11/Maple NOT same as Maple in Smath.
Uni reported some bugs in Maple. All CAS have bugs.

Cheers, Jean

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Wrote

You seem familiar with Maple.

Jean,

I use Maple for the first time. I found in SMath no possibility to simplify expressions (and also wrote a corresponding Feature Request). Maple plugin was the first possibility, which I found, to get readable expressions.

Both bugs here have nothing to do with Maple. To ensure that differentiation is performed by SMath, I have used Martins implementation of "symbeval()" function. Maple is used only to show differentiataion results in readable form.

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The script is correct as sanity check below
but result is NOT ! as proved ... Ah !
As it looks Maple is the guilty companion.

Hello Martin, Adventurist,

Martin, one day you gave me a trick "to be more divine".
Here is one to make Maple expansion "more divine".
There is a missing link somewhere.

Jean

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