AsymptoticEqual

AsymptoticEqual[f,g,x->x*] gives conditions for f(x)≍g(x) or f(x)∈Θ(g(x)) as x->x*.

AsymptoticEqual[f,g,{x1,…,xn}->{x1*,…,xn*}] gives conditions for f(x1,…,xn)≍g(x1,…,xn) or f(x1,…,xn)∈Θ(g(x1,…,xn)) as {x1,…,xn}->{x1*,…,xn*}.

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