"Mirifici Logarithmorum Canonis Descriptio, ejusque usus in utroque Trigonometría; ut etiam in omni logística mathematica, amplissimi, facillimi, et expeditissimi explicatio" napier :: Double -> Double napier 0.0 = 1.0 napier n = 1.0 / product [1..n] + napier (n - 1.0)
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