lemma
proved
tactic proof
deriv2_Jlog
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formal statement (Lean)
34lemma deriv2_Jlog (t : ℝ) : deriv (deriv Jlog) t = cosh t := by
proof body
Tactic-mode proof.
35 have h1 : deriv Jlog = sinh := by
36 funext s; exact deriv_Jlog s
37 rw [h1]
38 exact (hasDerivAt_sinh t).deriv
39
40/-- The calibration theorem: second derivative at zero equals 1 -/