4 files changed, 70 insertions, 7 deletions

diff --git a/CHANGES b/CHANGES
index 3cdcf5c..2b6b481 100644
--- a/CHANGES
+++ b/CHANGES
@@ -3,9 +3,11 @@
 
 - invlndet (inverse and log of determinant)
 
-- step, cond,
+- step, cond
 
-- find, assoc
+- find
+
+- assoc
 
 0.10.0.0
 ========
diff --git a/examples/bool.hs b/examples/bool.hs
new file mode 100644
index 0000000..9301689
--- /dev/null
+++ b/examples/bool.hs
@@ -0,0 +1,50 @@
+-- vectorized boolean operations defined in terms of step or cond
+
+import Numeric.LinearAlgebra
+
+infix  4  .==., ./=., .<., .<=., .>=., .>.
+infixr 3  .&&.
+infixr 2  .||.
+
+a .<.  b = step (b-a)
+a .<=. b = cond a b 1 1 0
+a .==. b = cond a b 0 1 0
+a ./=. b = cond a b 1 0 1
+a .>=. b = cond a b 0 1 1
+a .>.  b = step (a-b)
+
+a .&&. b  = step (a*b)
+a .||. b  = step (a+b)
+no a      = 1-a
+xor a b   = a ./=. b
+equiv a b = a .==. b
+imp a b   = no a .||. b
+
+taut x = minElement x == 1
+
+-- examples
+
+clip a b x = cond y b y y b where y = cond x a a x x
+
+disp = putStr . dispf 3
+
+eye n = ident n :: Matrix Double
+row = asRow . fromList    :: [Double] -> Matrix Double
+col = asColumn . fromList :: [Double] -> Matrix Double
+
+m = (3><4) [1..] :: Matrix Double
+
+p = row [0,0,1,1]
+q = row [0,1,0,1]
+
+main = do
+    print $ find (>6) m
+    disp $ assoc (6,8) 7 $ zip (find (/=0) (eye 5)) [10..]
+    disp $ m .>=. 10  .||.  m .<. 4
+    (disp . fromColumns . map flatten) [p, q, p.&&.q, p .||.q, p `xor` q, p `equiv` q, p `imp` q]
+    print $ taut $ (p `imp` q ) `equiv` (no q `imp` no p)
+    print $ taut $ (xor p q) `equiv` (p .&&. no q .||. no p .&&. q)
+    disp $ clip 3 8 m
+    disp $ col [1..7] .<=. row [1..5]
+    disp $ cond (col [1..3]) (row [1..4]) m 50 (3*m)
+
diff --git a/hmatrix.cabal b/hmatrix.cabal
index b8f23a1..daed1e5 100644
--- a/hmatrix.cabal
+++ b/hmatrix.cabal
@@ -54,6 +54,7 @@ extra-source-files: examples/tests.hs
                     examples/Real.hs
                     examples/vector.hs
                     examples/monadic.hs
+                    examples/bool.hs
 
 extra-source-files: lib/Numeric/LinearAlgebra/LAPACK/lapack-aux.h,
                     lib/Numeric/LinearAlgebra/LAPACK/clapack.h
diff --git a/lib/Numeric/ContainerBoot.hs b/lib/Numeric/ContainerBoot.hs
index e33857a..276eaa8 100644
--- a/lib/Numeric/ContainerBoot.hs
+++ b/lib/Numeric/ContainerBoot.hs
@@ -121,14 +121,24 @@ class (Complexable c, Fractional e, Element e) => Container c e where
     sumElements :: c e -> e
     -- | the product of elements (faster than using @fold@)
     prodElements :: c e -> e
-    -- | map (if x_i>0 then 1.0 else 0.0)
-    step :: RealFloat e => c e -> c e
+    -- | a more efficient implementation of @cmap (\x -> if x>0 then 1 else 0)@
+    step :: RealElement e => c e -> c e
     -- | find index of elements which satisfy a predicate
     find :: (e -> Bool) -> c e -> [IndexOf c]
     -- | create a structure from an association list
-    assoc :: IndexOf c -> e -> [(IndexOf c, e)] -> c e
-    -- | a vectorized form of case 'compare' a_i b_i of LT -> l_i; EQ -> e_i; GT -> g_i
-    cond :: RealFloat e => c e -> c e -> c e -> c e -> c e -> c e
+    assoc :: IndexOf c        -- ^ size
+          -> e                -- ^ default value
+          -> [(IndexOf c, e)] -- ^ association list
+          -> c e              -- ^ result
+
+    -- | element by element @case compare a b of LT -> l, EQ -> e, GT -> g@
+    cond :: RealElement e 
+         => c e -- ^ a
+         -> c e -- ^ b
+         -> c e -- ^ l 
+         -> c e -- ^ e
+         -> c e -- ^ g
+         -> c e -- ^ result
 
 --------------------------------------------------------------------------