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constraints = {A >= 0, B >= 0, A + 2 B == T, S == T*V + 2.4*B^3};
Simplify[Minimize[{T, constraints}, {A, B, T}, Reals], {S > 0, V >= 0}]

Above is the code trying to minimize the time consumption of an item trying to move S.

Its V0=V, Acc0=0.

It is required to perform three stages,

  1. keep V as V0, T=A
  2. Jerk(dS^3/d^3T) = 2.4, T=B
  3. Jerk = -2.4, T=B.

Obviously stage 2&3 are faster than stage 1, so I'm expected to see A->0 in the result. enter image description here But MMA gave me this above. The result of T is same with my solution by hand, but A and B are very weird.

I fully understand the meaning of Roots, and that the result could be expanded with ToRadicals, but that gives me very complex result with complex numbers.

But A was expected to be exactly 0. Other results is an error since I have declared [Reals] in Minimize.

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  • $\begingroup$ By setting S and V to specific numeric value, one can see A is indeed 0. The way to simplify the result is another story, though. (Such simplification can be rather troublesome, see e.g. mathematica.stackexchange.com/q/119346/1871 ) $\endgroup$ Commented Feb 13 at 1:35

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