division operator

field.py

@@ -39,6 +39,13 @@ class Field3d:
         else:
             return Field3d(self.data*other,self.origin,self.spacing)
 
+    def __truediv__(self,other):
+        if isinstance(other,Field3d):
+            assert self.has_same_grid(other), "Grid mismatch."
+            return Field3d(self.data/other.data,self.origin,self.spacing)
+        else:
+            return Field3d(self.data/other,self.origin,self.spacing)
+
     def  __radd__(self,other):
         return Field3d(other+self.data,self.origin,self.spacing)
 
@@ -72,6 +79,14 @@ class Field3d:
             self.data *= other
         return self
 
+    def __itruediv__(self,other):
+        if isinstance(other,Field3d):
+            assert self.has_same_grid(other), "Grid mismatch."
+            self.data /= other.data
+        else:
+            self.data /= other
+        return self
+
 # TBD: this should return another Field3d object
 #    def __getitem__(self,val):
 #        assert isinstance(val,tuple) and len(val)==3, "Field3d must be indexed by [ii,jj,kk]."