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diff --git a/packages/base/src/Internal/Conversion.hs b/packages/base/src/Internal/Conversion.hs
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+{-# LANGUAGE TypeFamilies #-}
+{-# LANGUAGE FlexibleContexts #-}
+{-# LANGUAGE FlexibleInstances #-}
+{-# LANGUAGE MultiParamTypeClasses #-}
+{-# LANGUAGE FunctionalDependencies #-}
+{-# LANGUAGE UndecidableInstances #-}
+
+-----------------------------------------------------------------------------
+-- |
+-- Module      :  Numeric.Conversion
+-- Copyright   :  (c) Alberto Ruiz 2010
+-- License     :  BSD3
+-- Maintainer  :  Alberto Ruiz
+-- Stability   :  provisional
+--
+-- Conversion routines
+--
+-----------------------------------------------------------------------------
+
+
+module Internal.Conversion (
+    Complexable(..), RealElement,
+    module Data.Complex
+) where
+
+import Internal.Vector
+import Internal.Matrix
+import Internal.Vectorized
+import Data.Complex
+import Control.Arrow((***))
+
+-------------------------------------------------------------------
+
+-- | Supported single-double precision type pairs
+class (Element s, Element d) => Precision s d | s -> d, d -> s where
+    double2FloatG :: Vector d -> Vector s
+    float2DoubleG :: Vector s -> Vector d
+
+instance Precision Float Double where
+    double2FloatG = double2FloatV
+    float2DoubleG = float2DoubleV
+
+instance Precision (Complex Float) (Complex Double) where
+    double2FloatG = asComplex . double2FloatV . asReal
+    float2DoubleG = asComplex . float2DoubleV . asReal
+
+-- | Supported real types
+class (Element t, Element (Complex t), RealFloat t)
+    => RealElement t
+
+instance RealElement Double
+instance RealElement Float
+
+
+-- | Structures that may contain complex numbers
+class Complexable c where
+    toComplex'   :: (RealElement e) => (c e, c e) -> c (Complex e)
+    fromComplex' :: (RealElement e) => c (Complex e) -> (c e, c e)
+    comp'        :: (RealElement e) => c e -> c (Complex e)
+    single'      :: Precision a b => c b -> c a
+    double'      :: Precision a b => c a -> c b
+
+
+instance Complexable Vector where
+    toComplex' = toComplexV
+    fromComplex' = fromComplexV
+    comp' v = toComplex' (v,constantD 0 (dim v))
+    single' = double2FloatG
+    double' = float2DoubleG
+
+
+-- | creates a complex vector from vectors with real and imaginary parts
+toComplexV :: (RealElement a) => (Vector a, Vector a) ->  Vector (Complex a)
+toComplexV (r,i) = asComplex $ flatten $ fromColumns [r,i]
+
+-- | the inverse of 'toComplex'
+fromComplexV :: (RealElement a) => Vector (Complex a) -> (Vector a, Vector a)
+fromComplexV z = (r,i) where
+    [r,i] = toColumns $ reshape 2 $ asReal z
+
+
+instance Complexable Matrix where
+    toComplex' = uncurry $ liftMatrix2 $ curry toComplex'
+    fromComplex' z = (reshape c *** reshape c) . fromComplex' . flatten $ z
+        where c = cols z
+    comp' = liftMatrix comp'
+    single' = liftMatrix single'
+    double' = liftMatrix double'
+