simp_rw [Real.fourierChar_apply]
E : Type u_1
inst✝ : TopologicalSpace E
f : E → ℝ
hf : Continuous f
⊢ Continuous fun x => ↑(Real.fourierChar (Multiplicative.ofAdd (f x)))
E : Type u_1
inst✝ : TopologicalSpace E
f : E → ℝ
hf : Continuous f
⊢ Continuous fun x => cexp (↑(2 * π * f x) * I)