lemma
proved
kappa_discreteness
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IndisputableMonolith.Flight.Geometry on GitHub at line 143.
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140This captures the “discrete pitch families” idea: per-turn growth is quantized in multiplicative
141steps of `φ^{d}` for `d : ℤ`.
142-/
143lemma kappa_discreteness (P : SpiralField.Params) (d : ℤ) :
144 SpiralField.perTurnMultiplier { kappa := P.kappa + d }
145 = SpiralField.perTurnMultiplier P * Real.rpow IndisputableMonolith.Constants.phi (d : ℝ) := by
146 -- `φ > 0` so we can use `Real.rpow_add`.
147 have hφpos : 0 < IndisputableMonolith.Constants.phi := IndisputableMonolith.Constants.phi_pos
148 -- Expand both sides and use `rpow_add` on the exponent `(κ + d)`.
149 simp [SpiralField.perTurnMultiplier, Real.rpow_add, hφpos, Int.cast_add]
150
151end SpiralLemmas
152
153end Geometry
154end Flight
155end IndisputableMonolith