Use a sensible definition for the all volumes positive test.

[spline3.git] / src / Cube.hs

diff --git a/src/Cube.hs b/src/Cube.hs
index 7b139a4741aff80a5bae666395aa61c5d45aff5d..1144a13168d7041800d67e18876d2e4dd369cdc7 100644 (file)
--- a/src/Cube.hs
+++ b/src/Cube.hs
@@ -28,15 +28,7 @@ import qualified Face (Face(Face, v0, v1, v2, v3))
 import FunctionValues
 import Misc (all_equal, disjoint)
 import Point
-import Tetrahedron (
-  Tetrahedron(..),
-  c,
-  b0,
-  b1,
-  b2,
-  b3,
-  volume
-  )
+import Tetrahedron (Tetrahedron(..), c, volume)
 import ThreeDimensional
 
 data Cube = Cube { h :: Double,
@@ -82,7 +74,7 @@ instance Show Cube where
 -- | The left-side boundary of the cube. See Sorokina and Zeilfelder,
 --   p. 76.
 xmin :: Cube -> Double
-xmin cube = (2*i' - 1)*delta / 2
+xmin cube = (i' - 1/2)*delta
     where
       i' = fromIntegral (i cube) :: Double
       delta = h cube
@@ -90,7 +82,7 @@ xmin cube = (2*i' - 1)*delta / 2
 -- | The right-side boundary of the cube. See Sorokina and Zeilfelder,
 --   p. 76.
 xmax :: Cube -> Double
-xmax cube = (2*i' + 1)*delta / 2
+xmax cube = (i' + 1/2)*delta
     where
       i' = fromIntegral (i cube) :: Double
       delta = h cube
@@ -98,7 +90,7 @@ xmax cube = (2*i' + 1)*delta / 2
 -- | The front boundary of the cube. See Sorokina and Zeilfelder,
 --   p. 76.
 ymin :: Cube -> Double
-ymin cube = (2*j' - 1)*delta / 2
+ymin cube = (j' - 1/2)*delta
     where
       j' = fromIntegral (j cube) :: Double
       delta = h cube
@@ -106,7 +98,7 @@ ymin cube = (2*j' - 1)*delta / 2
 -- | The back boundary of the cube. See Sorokina and Zeilfelder,
 --   p. 76.
 ymax :: Cube -> Double
-ymax cube = (2*j' + 1)*delta / 2
+ymax cube = (j' + 1/2)*delta
     where
       j' = fromIntegral (j cube) :: Double
       delta = h cube
@@ -114,7 +106,7 @@ ymax cube = (2*j' + 1)*delta / 2
 -- | The bottom boundary of the cube. See Sorokina and Zeilfelder,
 --   p. 76.
 zmin :: Cube -> Double
-zmin cube = (2*k' - 1)*delta / 2
+zmin cube = (k' - 1/2)*delta
     where
       k' = fromIntegral (k cube) :: Double
       delta = h cube
@@ -122,7 +114,7 @@ zmin cube = (2*k' - 1)*delta / 2
 -- | The top boundary of the cube. See Sorokina and Zeilfelder,
 --   p. 76.
 zmax :: Cube -> Double
-zmax cube = (2*k' + 1)*delta / 2
+zmax cube = (k' + 1/2)*delta
     where
       k' = fromIntegral (k cube) :: Double
       delta = h cube
@@ -673,15 +665,15 @@ prop_opposite_octant_tetrahedra_disjoint6 cube =
 
 
 -- | Since the grid size is necessarily positive, all tetrahedra
---   (which comprise cubes of positive volume) must have positive volume
---   as well.
+--   (which comprise cubes of positive volume) must have positive
+--   volume as well.
 prop_all_volumes_positive :: Cube -> Bool
 prop_all_volumes_positive cube =
-    null nonpositive_volumes
+    all (>= 0) volumes
     where
       ts = tetrahedra cube
       volumes = map volume ts
-      nonpositive_volumes = filter (<= 0) volumes
+
 
 -- | In fact, since all of the tetrahedra are identical, we should
 --   already know their volumes. There's 24 tetrahedra to a cube, so