Use a slightly more stable (I think?) formula for the {x,y,z}{min,max}.

diff --git a/src/Cube.hs b/src/Cube.hs
index 83f4da38f52638f300a655ce88dbfc3d46a9cd8a..3a997a4ab25e917eccd7e9e18587589b7bc98a32 100644 (file)
--- a/src/Cube.hs
+++ b/src/Cube.hs
@@ -74,7 +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
@@ -82,7 +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
@@ -90,7 +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
@@ -98,7 +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
@@ -106,7 +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
@@ -114,7 +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