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Question: assuming x::constant doesn't work with D?

Question:assuming x::constant doesn't work with D?

digerdiga 390 Maple 2019
assuming
June 30 2023
1

Hello,

I have this simple problem which doesn't want to work.

restart;
d := g -> (D@@2)(g) - x^2*g;
((d@@2)(g) assuming x::constant);

 

The result of the last line is:

(D@@4)(g) - 2*(D@@2)(x)*x*g - 2*D(x)^2*g - 4*D(x)*x*D(g) - x^2*(D@@2)(g) - x^2*((D@@2)(g) - x^2*g)

so Maple doesn't set D(x) to 0. On the other hand if I just write

D(x) assuming x::constant

then Mapel returns 0.

Similarly

D(f^k) assuming k::constant

just returns D(f^k) and not k*D(f)*f^(k-1) as the example in HELP suggests.
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