Choose a nearby value instead of zero when asked for a nonexistent function value.

diff --git a/src/FunctionValues.hs b/src/FunctionValues.hs
index 1d722b12b0f3132d028cbf53d01a9e584be977dd..8eb5bdb0d375ffdfe72eabb81097cc99c121e563 100644 (file)
--- a/src/FunctionValues.hs
+++ b/src/FunctionValues.hs
@@ -162,18 +162,19 @@ eval f (Quotient x y) = (eval f x) / (eval f y)
 
 -- | Takes a three-dimensional list of 'Double' and a set of 3D
 --   coordinates (i,j,k), and returns the value at (i,j,k) in the
---   supplied list. If there is no such value, zero is returned.
+--   supplied list. If there is no such value, we choose a nearby
+--   point and use its value.
 value_at :: Values3D -> Int -> Int -> Int -> Double
-value_at values i j k
-         | i < 0 = 0
-         | j < 0 = 0
-         | k < 0 = 0
-         | xsize <= i = 0
-         | ysize <= j = 0
-         | zsize <= k = 0
-         | otherwise = idx values i j k
+value_at v3d i j k
+         | i < 0 = value_at v3d 0 j k
+         | j < 0 = value_at v3d i 0 k
+         | k < 0 = value_at v3d i j 0
+         | xsize <= i = value_at v3d xsize j k
+         | ysize <= j = value_at v3d i ysize k
+         | zsize <= k = value_at v3d i j zsize
+         | otherwise = idx v3d i j k
   where
-    (xsize, ysize, zsize) = dims values
+    (xsize, ysize, zsize) = dims v3d
 
 
 -- | Given a three-dimensional list of 'Double' and a set of 3D