RosettaCodeData/Task/Fibonacci-sequence/Idris/fibonacci-sequence-1.idris
2016-12-05 23:44:36 +01:00

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fibAnalytic : Nat -> Double
fibAnalytic n =
floor $ ((pow goldenRatio n) - (pow (-1.0/goldenRatio) n)) / sqrt(5)
where goldenRatio : Double
goldenRatio = (1.0 + sqrt(5)) / 2.0