misc: make builtin grid unit spacing

devito/builtins/initializers.py

@@ -179,7 +179,9 @@ def fset(f, g):
     # Create the padded grid:
     objective_domain = ObjectiveDomain(lw)
     shape_padded = tuple([np.array(s) + 2*l for s, l in zip(shape, lw)])
-    grid = dv.Grid(shape=shape_padded, subdomains=objective_domain)
+    extent_padded = tuple([s-1 for s in shape_padded])
+    grid = dv.Grid(shape=shape_padded, subdomains=objective_domain,
+                   extent=extent_padded)
 
     f_c = dv.Function(name='f_c', grid=grid, space_order=2*max(lw), dtype=dtype)
     f_o = dv.Function(name='f_o', grid=grid, dtype=dtype)

devito/finite_differences/finite_difference.py

@@ -166,7 +166,8 @@ def make_derivative(expr, dim, fd_order, deriv_order, side, matvec, x0, coeffici
 
     # Adimensional weight from custom coeffs need to multiply by h^order
     scale = None
-    if wdim is None and not weights[0].has(dim.spacing):
+    if wdim is None and not all(w.has(dim.spacing) for w in weights if w != 0):
+        print(weights)
         scale = dim.spacing**(-deriv_order)
 
     # Transpose the FD, if necessary