Index: /issm/trunk-jpl/src/m/geometry/slope.py
===================================================================
--- /issm/trunk-jpl/src/m/geometry/slope.py	(revision 27524)
+++ /issm/trunk-jpl/src/m/geometry/slope.py	(revision 27525)
@@ -34,6 +34,6 @@
 
     summation = np.array([[1], [1], [1]])
-    sx = np.dot(surf[index - 1, 0] * alpha, summation).reshape(-1, )
-    sy = np.dot(surf[index - 1, 0] * beta, summation).reshape(-1, )
+    sx = np.dot(surf[index - 1] * alpha, summation).reshape(-1, )
+    sy = np.dot(surf[index - 1] * beta, summation).reshape(-1, )
 
     s = np.sqrt(sx**2 + sy**2)