Basic expression parsing

1 files changed, 0 insertions, 95 deletions

diff --git a/src/equation.hs b/src/equation.hs
deleted file mode 100644
index f332131..0000000
--- a/src/equation.hs
+++ /dev/null
@@ -1,95 +0,0 @@
-module Equation
-( Equation (..)
-, Polynomial
-, Term (..)
-, degree
-, reduce
-, solve
-, filterNull
-) where
-
-import Data.List
-
-
-data Equation = Equation { left :: Polynomial, right :: Polynomial }
-type Polynomial = [Term]
-data Term = Term { coefficient :: Float, exponent :: Int }
-
-instance Eq Term where
-    (Term _ e1) == (Term _ e2) = e1 == e2
-
-instance Ord Term where
-    compare (Term _ e1) (Term _ e2) = compare e1 e2
-
-instance Show Term where
-    show (Term 0 e) = ""
-    show (Term c 0) = show (round c)
-    show (Term c e) = show (round c) ++ " * X^" ++ show e
-
-instance Show Equation where
-    show (Equation l r) = showPolynomial (filterNull l)
-                          ++ " = "
-                          ++ showPolynomial (filterNull r)
-        where showPolynomial [] = "0"
-              showPolynomial p  = dropWhile (`elem` " +") $ foldl f "" (map show p)
-                where f s "" = s
-                      f s (c:cs)
-                        | c == '-'  = s ++ " - " ++ cs
-                        | otherwise = s ++ " + " ++ (c:cs)
-
-
-filterNull :: Polynomial -> Polynomial
-filterNull = filter (\t -> coefficient t /= 0)
-
-equationMap :: (Polynomial -> Polynomial) -> Equation -> Equation
-equationMap f (Equation l r) = Equation (f l) (f r)
-
-degree :: Polynomial -> Int
-degree [] = 0
-degree p  = Equation.exponent (maximum p)
-
-reduce :: Equation -> Equation
-reduce equ = Equation (merge (left stdForm) (right stdForm)) []
-    where stdForm = equationMap (\a -> (reducePolynomial $ sort a)) equ
-          merge [] rs = rs
-          merge ls [] = ls
-          merge (l:ls) (r:rs)
-            | l == r = (subTerm l r) : merge ls rs
-            | l < r  = l : merge ls (r:rs)
-            | r < l  = r : merge (l:ls) rs
-            where subTerm (Term c1 e) (Term c2 _) = Term (c1 - c2) e
-          reducePolynomial []         = []
-          reducePolynomial [t]        = [t]
-          reducePolynomial (t1:t2:ts)
-            | t1 == t2  = (addTerm t1 t2) : reducePolynomial ts
-            | otherwise = t1 : reducePolynomial (t2:ts)
-            where addTerm (Term c1 e) (Term c2 _) = Term (c1 + c2) e
-
-solveDegree2 :: Float -> Float -> Float -> [Float]
-solveDegree2 a b c
-    | phi < 0   = []
-    | phi == 0  = [(-b) / (2.0 * a)]
-    | phi > 0   = [ (-b + mySqrt phi) / (2.0 * a) -- not alowed
-                  , (-b - mySqrt phi) / (2.0 * a)
-                  ]
-    where phi = b * b - 4.0 * a * c
-
-solveDegree1 :: Float -> Float -> Float
-solveDegree1 b c = -c / b
-
-solve :: Polynomial -> [Float]
-solve [t0]         = []
-solve [t0, t1]     = [solveDegree1 (coefficient t1) (coefficient t0)]
-solve [t0, t1, t2] = solveDegree2 (coefficient t2) (coefficient t1) (coefficient t0)
-solve _            = undefined
-
-mySqrt :: Float -> Float
-mySqrt n
-  | n < 0     = undefined
-  | otherwise = mySqrt' (n / 2)
-    where mySqrt' x = if abs (x * x - n) < 0.01
-                         then x
-                         else mySqrt' xn
-            where xn = b - (a * a) / (2 * b)
-                    where a = (n - x * x) / (2 * x)
-                          b = x + a