dsl: SparseFunction coordinates now always real

Author: EdCaunt

devito/operations/interpolators.py

@@ -472,7 +472,8 @@ def _weights(self, subdomain=None):
     @cached_property
     def _point_symbols(self):
         """Symbol for coordinate value in each Dimension of the point."""
-        return DimensionTuple(*(Symbol(name='p%s' % d, dtype=self.sfunction.dtype)
+        dtype = self.sfunction.coordinates.dtype
+        return DimensionTuple(*(Symbol(name='p%s' % d, dtype=dtype)
                                 for d in self.grid.dimensions),
                               getters=self.grid.dimensions)
 

devito/types/sparse.py

@@ -202,6 +202,12 @@ def __subfunc_setup__(self, suffix, keys, dtype=None, inkwargs=False, **kwargs):
             else:
                 dtype = dtype or self.dtype
 
+        # Complex coordinates are not valid, so fall back to corresponding
+        # real floating point type if dtype is complex.
+        if issubclass(dtype, np.complexfloating):
+            dtype = {np.complex64: np.float32,
+                     np.complex128: np.float64}.get(dtype, np.float32)
+
         sf = SparseSubFunction(
             name=name, dtype=dtype, dimensions=dimensions,
             shape=shape, space_order=0, initializer=key, alias=self.alias,