X-Git-Url: http://gitweb.michael.orlitzky.com/?a=blobdiff_plain;f=src%2FLinear%2FMatrix.hs;h=a5fbb8403b0832becf04b0d48a68be4f0725345c;hb=9ef91ad4ec3a5c0966f0850d40310722b6c38b68;hp=660330245b330b840bcb848af512b7d6561e217f;hpb=4b5f216ca9e1890c40bbf8053cfed94e3961849f;p=numerical-analysis.git

diff --git a/src/Linear/Matrix.hs b/src/Linear/Matrix.hs
index 6603302..a5fbb84 100644
--- a/src/Linear/Matrix.hs
+++ b/src/Linear/Matrix.hs
@@ -152,60 +152,47 @@ fromList vs = Mat (V.fromList $ map V.fromList vs)
 
 -- | Unsafe indexing.
 (!!!) :: (Arity m, Arity n) => Mat m n a -> (Int, Int) -> a
-(!!!) m (i, j) = (row m i) ! j
+(!!!) (Mat rows) (i, j) = (rows ! i) ! j
+
 
 -- | Safe indexing.
-(!!?) :: Mat m n a -> (Int, Int) -> Maybe a
-(!!?) m@(Mat rows) (i, j)
+(!!?) :: (Arity m, Arity n) => Mat m n a -> (Int, Int) -> Maybe a
+(!!?) matrix (i, j)
   | i < 0 || j < 0 = Nothing
-  | i > V.length rows = Nothing
-  | otherwise = if j > V.length (row m j)
-                then Nothing
-                else Just $ (row m j) ! j
+  | i > (nrows matrix) - 1 = Nothing
+  | j > (ncols matrix) - 1 = Nothing
+  | otherwise = Just $ matrix !!! (i,j)
 
 
 -- | The number of rows in the matrix.
 nrows :: forall m n a. (Arity m) => Mat m n a -> Int
 nrows _ = arity (undefined :: m)
 
+
 -- | The number of columns in the first row of the
 --   matrix. Implementation stolen from Data.Vector.Fixed.length.
 ncols :: forall m n a. (Arity n) => Mat m n a -> Int
 ncols _ = arity (undefined :: n)
 
 
--- | Return the @i@th row of @m@. Unsafe.
-row :: Mat m n a -> Int -> (Vec n a)
-row (Mat rows) i = rows ! i
-
-
 -- | Return the @i@th row of @m@ as a matrix. Unsafe.
-row' :: (Arity m, Arity n) => Mat m n a -> Int -> Row n a
-row' m i =
+row :: (Arity m, Arity n) => Mat m n a -> Int -> Row n a
+row m i =
   construct lambda
   where
     lambda _ j = m !!! (i, j)
 
 
--- | Return the @j@th column of @m@. Unsafe.
-column :: Mat m n a -> Int -> (Vec m a)
-column (Mat rows) j =
-  V.map (element j) rows
-  where
-    element = flip (!)
-
-
 -- | Return the @j@th column of @m@ as a matrix. Unsafe.
-column' :: (Arity m, Arity n) => Mat m n a -> Int -> Col m a
-column' m j =
+column :: (Arity m, Arity n) => Mat m n a -> Int -> Col m a
+column m j =
   construct lambda
   where
     lambda i _ = m !!! (i, j)
 
 
 -- | Transpose @m@; switch it's columns and its rows. This is a dirty
---   implementation.. it would be a little cleaner to use imap, but it
---   doesn't seem to work.
+--   implementation, but I don't see a better way.
 --
 --   TODO: Don't cheat with fromList.
 --
@@ -216,9 +203,10 @@ column' m j =
 --   ((1,3),(2,4))
 --
 transpose :: (Arity m, Arity n) => Mat m n a -> Mat n m a
-transpose m = Mat $ V.fromList column_list
+transpose matrix =
+  construct lambda
   where
-    column_list = [ column m i | i <- [0..(ncols m)-1] ]
+    lambda i j = matrix !!! (j,i)
 
 
 -- | Is @m@ symmetric?
@@ -270,6 +258,7 @@ identity_matrix :: (Arity m, Ring.C a) => Mat m m a
 identity_matrix =
   construct (\i j -> if i == j then (fromInteger 1) else (fromInteger 0))
 
+
 -- | Given a positive-definite matrix @m@, computes the
 --   upper-triangular matrix @r@ with (transpose r)*r == m and all
 --   values on the diagonal of @r@ positive.
@@ -816,11 +805,11 @@ colzipwith f c1 c2 =
 --   Examples:
 --
 --   >>> let m = fromList [[1,2],[3,4]] :: Mat2 Int
---   >>> matmap (^2) m
+--   >>> map2 (^2) m
 --   ((1,4),(9,16))
 --
-matmap :: (a -> b) -> Mat m n a -> Mat m n b
-matmap f (Mat rows) =
+map2 :: (a -> b) -> Mat m n a -> Mat m n b
+map2 f (Mat rows) =
   Mat $ V.map g rows
   where
     g = V.map f