diff --git a/Orthogonals.lhs b/Orthogonals.lhs
--- a/Orthogonals.lhs
+++ b/Orthogonals.lhs
@@ -304,7 +304,7 @@
         by some algorithms. So far we have been able to avoid this.
 <pre>
 
-> class Scalar a where
+> class Eq a => Scalar a where
 >     coupled    :: a->a
 >     norm       :: [a] -> a
 >     almostZero :: a -> Bool
@@ -317,10 +317,10 @@
 >     scaled       = scaled'
 
 > instance Scalar Float where
->    coupled x    = x
->    norm u       = sqrt (bra_ket u u)
->    almostZero x = (abs x) < 1.0e-8
->    scaled       = scaled'
+>     coupled x    = x
+>     norm u       = sqrt (bra_ket u u)
+>     almostZero x = (abs x) < 1.0e-8
+>     scaled       = scaled'
 
 > instance (Integral a) => Scalar (Ratio a) where
 >     coupled x    = x
@@ -380,15 +380,11 @@
 
 > normalized :: (Scalar a, Fractional a) => [a] -> [a]
 > normalized u =
->       [uk/n | uk <- u]
->       where
->           n = norm u
+>       map (/norm u) u
 
 > scaled' :: (Fractional t, Ord t) => [t] -> [t]
 > scaled' u =
->       [uk/um | uk <- u]
->       where
->           um = maximum [abs uk| uk <- u]
+>       map (/norminf u) u
 
 </pre>
 <hr>
@@ -783,7 +779,7 @@
 
 <pre>
 
-> one_ket_solution :: (Fractional a, Scalar a) => [[a]] -> [a] -> [a]
+> one_ket_solution :: (Scalar a, Fractional a) => [[a]] -> [a] -> [a]
 > one_ket_solution a b =
 >     --
 >     -- List representing vector |x>, which is
@@ -951,7 +947,7 @@
 
 <pre>
 
-> factors_QR :: (Fractional a, Scalar a) => [[a]] -> ([[a]],[[a]])
+> factors_QR :: (Scalar a, Fractional a) => [[a]] -> ([[a]],[[a]])
 > factors_QR a =
 >       --
 >       -- A pair of matrices (Q, R), such that
@@ -979,7 +975,7 @@
 
 <pre>
 
-> determinant :: (Fractional a, Scalar a) => [[a]] -> a
+> determinant :: (Scalar a, Fractional a) => [[a]] -> a
 > determinant a =
 >    let (q,r) = factors_QR a
 >    -- matrix Q is not normed so we have to respect the norms of its rows
@@ -1188,7 +1184,7 @@
 <pre>
 
 
-> similar_to :: (Fractional a, Scalar a) => [[a]] -> [[a]]
+> similar_to :: (Scalar a, Fractional a) => [[a]] -> [[a]]
 > similar_to a =
 >       --
 >       -- List of columns of matrix A1 similar to A
@@ -1201,7 +1197,7 @@
 >       where
 >           (q,r) = factors_QR a
 
-> iterated_eigenvalues :: (Scalar a1, Fractional a1, Num a) => [[a1]] -> a -> [[a1]]
+> iterated_eigenvalues :: (Scalar a1, Fractional a1, Eq a, Num a) => [[a1]] -> a -> [[a1]]
 > iterated_eigenvalues a n
 >       --
 >       -- List of vectors representing
@@ -1215,7 +1211,7 @@
 >       | otherwise = (diagonals a)
 >                     : iterated_eigenvalues (similar_to a) (n-1)
 
-> eigenvalues :: (Scalar a1, Fractional a1, Num a) => [[a1]] -> a -> [a1]
+> eigenvalues :: (Scalar a1, Fractional a1, Eq a, Num a) => [[a1]] -> a -> [a1]
 > eigenvalues a n
 >       --
 >       -- Eigenvalues of matrix A
@@ -1789,24 +1785,14 @@
 >       --
 >       -- Unit square matrix of with dimensions m x m
 >       --
->       [g 0 k | k <- [0..(m-1)]]
->       where
->       g i k
->           | i == m    = []
->           | i == k    = 1:(g (i+1) k)
->           | otherwise = 0:(g (i+1) k)
->
+>       [ [ if j==k then 1 else 0 | j <- [0 .. m-1] ] | k <- [0 .. m-1]]
 
 > unit_vector :: Num a => Int -> Int -> [a]
 > unit_vector i m =
 >       --
 >       -- Unit vector of length m
 >       -- with 1 at position i, zero otherwise
->       [g i k| k <- [0..(m-1)]]
->       where
->           g j k
->               | j == k    = 1
->               | otherwise = 0
+>       map (\k -> if k==i then 1 else 0) [0 .. m-1]
 
 > diagonals :: [[a]] -> [a]
 > diagonals a =
diff --git a/QuantumVector.lhs b/QuantumVector.lhs
--- a/QuantumVector.lhs
+++ b/QuantumVector.lhs
@@ -1129,7 +1129,7 @@
 >     showsPrec n (j :<+ k) = showsPrec n j . showString " + " . showsPrec n k
 
 
-> showsScalar :: (RealFloat t) => Int -> Complex t -> String -> String
+> showsScalar :: (Show t, RealFloat t) => Int -> Complex t -> String -> String
 > showsScalar n x@(a :+ b)
 >     | b == 0    = showsPrec n a . showString " "
 >     | otherwise = showString "(" .showsPrec n x . showString ") "
diff --git a/Roots.hs b/Roots.hs
--- a/Roots.hs
+++ b/Roots.hs
@@ -77,20 +77,12 @@
           u y a b = a + b*y
 
 polynomial_derivative :: Num a => [a] -> [a]
-polynomial_derivative as
+polynomial_derivative as =
       --
       -- List of coefficients for derivative of polynomial
       -- a0 + a1 x + a2 x^2 ...
       --
-      | as == []  = []
-      | otherwise = deriv 1 (drop 1 as) []
-      where
-          deriv n bs cs
-             | bs == []   = reverse2 cs
-             | otherwise  = deriv (n+1) (tail bs) ((n*(head bs)):cs)
-          reverse2 cs
-              | cs == []  = []
-              | otherwise = reverse cs
+      zipWith (*) (iterate (1+) 1) (drop 1 as)
 
 -----------------------------------------------------------------------------
 --
diff --git a/numeric-quest.cabal b/numeric-quest.cabal
--- a/numeric-quest.cabal
+++ b/numeric-quest.cabal
@@ -1,5 +1,5 @@
 Name:           numeric-quest
-Version:        0.1.1.3
+Version:        0.2
 License:        GPL
 License-File:   LICENSE
 Author:         Jan Skibinski
@@ -17,7 +17,7 @@
   README
 
 Source-Repository this
-  Tag:         0.1.1.3
+  Tag:         0.2
   Type:        darcs
   Location:    http://code.haskell.org/~thielema/numeric-quest/