theorem
proved
tactic proof
measurement_bridge_C_eq_2A
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formal statement (Lean)
152theorem measurement_bridge_C_eq_2A (rot : TwoBranchRotation) :
153 pathAction (pathFromRotation rot) = 2 * rateAction rot := by
proof body
Tactic-mode proof.
154 unfold pathAction pathFromRotation rateAction
155 simp
156 have hkernel : ∫ ϑ in (0)..(π/2 - rot.θ_s),
157 Jcost (recognitionProfile (ϑ + rot.θ_s)) =
158 2 * ∫ ϑ in (0)..(π/2 - rot.θ_s), Real.cot (ϑ + rot.θ_s) :=
159 kernel_integral_match rot.θ_s rot.θ_s_bounds
160 rw [hkernel]
161 have h_subst :
162 ∫ ϑ in (0)..(π/2 - rot.θ_s), Real.cot (ϑ + rot.θ_s)
163 = ∫ θ in rot.θ_s..(π/2), Real.cot θ := by
164 simpa [sub_eq_add_neg, add_comm, add_left_comm, add_assoc]
165 using
166 (intervalIntegral.integral_comp_add_right
167 (a := (0 : ℝ)) (b := π/2 - rot.θ_s)
168 (f := fun θ => Real.cot θ) (d := rot.θ_s))
169 have hI := integral_cot_from_theta rot.θ_s rot.θ_s_bounds
170 have htan :
171 ∫ ϑ in (0)..(π/2 - rot.θ_s), Real.cot (ϑ + rot.θ_s)
172 = - Real.log (Real.sin rot.θ_s) := by
173 simpa [h_subst] using hI
174 simp [htan, two_mul, mul_left_comm, mul_assoc]
175
176/-- Weight bridge: w = exp(-C) = exp(-2A) -/