theorem
proved
tactic proof
tick4_is_neg1
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formal statement (Lean)
64theorem tick4_is_neg1 : eightTickPhase 4 = -1 := by
proof body
Tactic-mode proof.
65 unfold eightTickPhase
66 simp only [Fin.val_four, Nat.cast_ofNat]
67 have h : I * (4 * Real.pi / 4) = I * Real.pi := by ring
68 rw [h]
69 rw [Complex.exp_mul_I, Complex.cos_pi, Complex.sin_pi]
70 simp
71
72/-! ## Rotation and Multiplication -/
73
74/-- Multiplication by i is rotation by π/2 (2 ticks). -/