Averages/Pythagorean means: Difference between revisions
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(→JS ES6: Updated primitives, consolidated test with mapFromList and applicative ap) |
(→{{header|Haskell}}: Added an alternative, defining the functions applicatively, and testing with (and zipWith (>=))) |
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=={{header|Haskell}}== |
=={{header|Haskell}}== |
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====One generalized function==== |
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The [[wp:Generalized mean|general function]] given here yields an arithmetic mean when its first argument is <code>1</code>, a geometric mean when its first argument is <code>0</code>, and a harmonic mean when its first argument is <code>-1</code>. |
The [[wp:Generalized mean|general function]] given here yields an arithmetic mean when its first argument is <code>1</code>, a geometric mean when its first argument is <code>0</code>, and a harmonic mean when its first argument is <code>-1</code>. |
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mapM_ (\(t,m) -> putStrLn $ t : ": " ++ show m) ms |
mapM_ (\(t,m) -> putStrLn $ t : ": " ++ show m) ms |
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putStrLn $ " a >= g >= h is " ++ show ((\(_,[a,g,h])-> a>=g && g>=h) (unzip ms))</lang> |
putStrLn $ " a >= g >= h is " ++ show ((\(_,[a,g,h])-> a>=g && g>=h) (unzip ms))</lang> |
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====Three applicatively defined functions==== |
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These three functions share the same liftM2 structure, which can be expressed applicatively as '''pure f <*> f1 <*> f2''' |
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<lang haskell>import Data.List (genericLength) |
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-- ARITHMETIC, GEOMETRIC AND HARMONIC MEANS ----------------------- |
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arithmetic, geometric, harmonic :: [Double] -> Double |
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arithmetic = pure (/) <*> sum <*> genericLength |
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geometric = pure (**) <*> product <*> ((1 /) . genericLength) |
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harmonic = pure (/) <*> genericLength <*> foldr ((+) . (1 /)) 0 |
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-- TEST ----------------------------------------------------------- |
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xs :: [Double] |
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xs = [arithmetic, geometric, harmonic] <*> [[1 .. 10]] |
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main :: IO () |
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main = |
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(putStrLn . unlines) |
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[ zip ["Arithmetic", "Geometric", "Harmonic"] xs >>= show |
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, mappend "\n A >= G >= H is " $ -- |
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(show . and) $ zipWith (>=) xs (tail xs) |
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]</lang> |
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{{Out}} |
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<pre>("Arithmetic",5.5)("Geometric",4.528728688116765)("Harmonic",3.414171521474055) |
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a >= g >= h is True</pre> |
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=={{header|HicEst}}== |
=={{header|HicEst}}== |
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