Question:Take Exponent in Maple

Question:Take Exponent in Maple

Maple

In Maple, to take the exponent of a term of the form $x^a$, we can define

Exponent := proc(x::^)

local r;

r := op(2, x);

return(r);

end proc:

This also works for a term of the form $Y[1,3]^{-1/3}$.

But this does not work for taking exponent of a term of the form $Y[1,3]$. How to define a function $f$ in Maple, such that $f(Y[1,3]^{a}) = a$ for any $a \in \mathbb{Q}$? Thank you very much.

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