2 files changed, 8 insertions, 3 deletions

diff --git a/lib/Data/Packed/Internal/Matrix.hs b/lib/Data/Packed/Internal/Matrix.hs
index 89a162a..58b325c 100644
--- a/lib/Data/Packed/Internal/Matrix.hs
+++ b/lib/Data/Packed/Internal/Matrix.hs
@@ -348,7 +348,7 @@ foreign import ccall safe "aux.h constantC"
 @> constant 2 7
 7 |> [2.0,2.0,2.0,2.0,2.0,2.0,2.0]@
 -}
-constant :: Field a => a -> Int -> Vector a
+constant :: Double -> Int -> Vector Double
 constant = constantD
 
 --------------------------------------------------------------------------
@@ -361,6 +361,11 @@ conj v = asComplex $ cdat $ reshape 2 (asReal v) `multiply` diag (fromList [1,-1
 toComplex :: (Vector Double, Vector Double) ->  Vector (Complex Double)
 toComplex (r,i) = asComplex $ cdat $ fromColumns [r,i]
 
+-- | the inverse of 'toComplex'
+fromComplex :: Vector (Complex Double) -> (Vector Double, Vector Double)
+fromComplex z = (r,i) where
+    [r,i] = toColumns $ reshape 2 $ asReal z
+
 -- | converts a real vector into a complex representation (with zero imaginary parts)
 comp :: Vector Double -> Vector (Complex Double)
 comp v = toComplex (v,constant 0 (dim v))
diff --git a/lib/Data/Packed/Matrix.hs b/lib/Data/Packed/Matrix.hs
index 01e8133..fc08ce4 100644
--- a/lib/Data/Packed/Matrix.hs
+++ b/lib/Data/Packed/Matrix.hs
@@ -75,12 +75,12 @@ diagRect s r c
     | r == c    = diag s
     | r < c     = trans $ diagRect s c r
     | r > c     = joinVert  [diag s , zeros (r-c,c)]
-    where zeros (r,c) = reshape c $ constant 0 (r*c)
+    where zeros (r,c) = reshape c $ constantD 0 (r*c)
 
 takeDiag :: (Field t) => Matrix t -> Vector t
 takeDiag m = fromList [cdat m `at` (k*cols m+k) | k <- [0 .. min (rows m) (cols m) -1]]
 
-ident :: (Num t, Field t) => Int -> Matrix t
+ident :: Int -> Matrix Double
 ident n = diag (constant 1 n)
 
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