X-Git-Url: http://gitweb.michael.orlitzky.com/?a=blobdiff_plain;f=src%2FGrid.hs;h=4b75185ad19b31b4922e5485105b069ec56dba96;hb=58cf11569acb270995d2de924dda03ef526647e2;hp=e67ac764022a82ab974593395482ec4d6cfa81fc;hpb=89b8b6e94fcc944a1f4611811265f3c6217af850;p=spline3.git

diff --git a/src/Grid.hs b/src/Grid.hs
index e67ac76..4b75185 100644
--- a/src/Grid.hs
+++ b/src/Grid.hs
@@ -1,13 +1,12 @@
 -- | The Grid module just contains the Grid type and two constructors
 --   for it. We hide the main Grid constructor because we don't want
 --   to allow instantiation of a grid with h <= 0.
-module Grid (empty_grid,
-             function_values,
-             Grid,
-             h,
-             make_grid)
+module Grid
 where
 
+import Cube (Cube(Cube))
+import FunctionValues
+
 -- | Our problem is defined on a Grid. The grid size is given by the
 --   positive number h. The function values are the values of the
 --   function at the grid points, which are distance h from one
@@ -28,3 +27,34 @@ make_grid grid_size values
 -- | Creates an empty grid with grid size 1.
 empty_grid :: Grid
 empty_grid = Grid 1 [[[]]]
+
+
+-- | Returns a three-dimensional list of cubes centered on the grid
+--   points of g with the appropriate 'FunctionValues'.
+cubes :: Grid -> [[[Cube]]]
+cubes g
+    | fvs == [[[]]] = [[[]]]
+    | head fvs == [[]] = [[[]]]
+    | otherwise =
+        [[[ Cube (h g) i j k (make_values fvs i j k) | i <- [0..xsize]]
+              | j <- [0..ysize]]
+              | k <- [0..zsize]]
+    where
+      fvs = function_values g
+      zsize = (length fvs) - 1
+      ysize = (length $ head fvs) - 1
+      xsize = (length $ head $ head fvs) - 1
+
+
+-- | Takes a grid and a position as an argument and returns the cube
+--   centered on that position. If there is no cube there (i.e. the
+--   position is outside of the grid), it will return 'Nothing'.
+cube_at :: Grid -> Int -> Int -> Int -> Maybe Cube
+cube_at g i j k
+    | i < 0 = Nothing
+    | j < 0 = Nothing
+    | k < 0 = Nothing
+    | i >= length (cubes g) = Nothing
+    | j >= length ((cubes g) !! i) = Nothing
+    | k >= length (((cubes g) !! i) !! j) = Nothing
+    | otherwise = Just $ (((cubes g) !! i) !! j) !! k