94 lines
2.2 KiB
Haskell
94 lines
2.2 KiB
Haskell
module Data.Number.Internal
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( operator
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, cut
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, first
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, rest
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, split
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) where
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import Data.Number.Types
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import Data.Ratio
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import Numeric.Peano
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type Matrix = (Whole, Whole, Whole, Whole, Whole, Whole, Whole, Whole)
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operator :: Matrix -> Number -> Number -> Number
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operator c x y =
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case operator' c x y False of
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[] -> E
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m -> if head m < 0
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then M $ fromList (map toNat m)
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else fromList (map toNat m)
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where
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fromList [] = E
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fromList (x:xs) = x :| fromList xs
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operator' :: Matrix -> Number -> Number -> Bool -> [Whole]
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operator' (_,_,_,_,0,0,0,0) _ _ _ = []
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operator' (a,b,c,d,e,f,g,h) x y end
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| t = r : operator' (e, f, g, h, a-e*r, b-f*r, c-g*r, d-h*r) x y end
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| x/=E && s = operator' (b, a+b*p, d, c+d*p, f, e+f*p, h, g+h*p) x' y end
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| x==E && s = operator' (b, b, d, d, f, f, h, h) E y end
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| y/=E = operator' (c, d, a+c*q, b+d*q, g, h, e+g*q, f+h*q) x y' end
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| otherwise = operator' (c, d, c, d, g, h, g, h) x E True
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where
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r = a // e
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(p, x') = split x
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(q, y') = split y
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t = not (any (==0) [e,f,g,h]) && all (==r) [b//f, c//g, d//h]
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s | end = True
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| any (==0) [f,g,e,h] = False
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| otherwise = abs (b%f - a%e) > abs (c%g - a%e)
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cut :: Nat -> Number -> Number
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cut _ E = E
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cut n (M x) = M (cut n x)
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cut n _ | n <= 0 = E
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cut n (x :| xs) = x :| cut (n-1) xs
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split :: Number -> (Whole, Number)
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split x = (first x, rest x)
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first :: Number -> Whole
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first E = 0
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first (M E) = 0
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first (M (x:|_)) = Whole x Neg
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first (x:|_) = Whole x Pos
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rest :: Number -> Number
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rest E = E
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rest (M E) = E
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rest (M x) = M (rest x)
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rest (_:|xs) = xs
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-- Peano arithmethics --
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toNat :: Whole -> Nat
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toNat (Whole n _) = n
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(//) :: Integral a => a -> a -> a
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(//) = quot
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instance Real Whole where
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toRational = (%1) . toInteger
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instance Integral Whole where
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toInteger (Whole z Pos) = (fromPeano z)
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toInteger (Whole z Neg) = -(fromPeano z)
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quotRem (Whole a s) (Whole b s') = (Whole q sign, Whole r Pos)
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where
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q = quot a b
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r = a - q * b
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sign | s == s' && s == Pos = Pos
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| s == s' && s == Neg = Pos
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| otherwise = Neg
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