python: slope.py: Use cell size in index definition.

* python/slope.py (dzdy): Update note.

1 files changed, 2 insertions, 2 deletions

diff --git a/python/slope.py b/python/slope.py
index 29d967e..03839e5 100755
--- a/python/slope.py
+++ b/python/slope.py
@@ -62,8 +62,8 @@ dzdy = np.zeros((NYCELL, NXCELL))
 for i in range(1, NYCELL + 1):
     for j in range(1, NXCELL + 1):
         dzdy[i-1, j-1] = (z3[i+1, j] - z3[i-1, j])/(2.0*DY)
-# array index and co-ordinates are related by:
-#            index = (co-ord - 0.25)*2
+# Note: dz/dy index and co-ordinates are related by:
+#            index = int(co-ord/DX - 0.5)
 #print("dzdy", dzdy[NYCELL-1, 280:301])
 #print("elev", elev[NYCELL-1, 280:301])