Fix derivative taking in line Taylor

Author: inducer

sumpy/expansion/local.py

@@ -149,9 +149,12 @@ def coefficients_from_source(self, kernel, avec, bvec, rscale, sac=None):
 
     def evaluate(self, tgt_kernel, coeffs, bvec, rscale, sac=None):
         # no point in heeding rscale here--just ignore it
-        return sym.Add(*(
-                coeffs[self.get_storage_index(i)] / math.factorial(i)
-                for i in self.get_coefficient_identifiers()))
+
+        # NOTE: We can't meaningfully apply target derivatives here.
+        # Instead, this is handled in LayerPotentialBase._evaluate.
+        return  sym.Add(*(
+                    coeffs[self.get_storage_index(i)] / math.factorial(i)
+                    for i in self.get_coefficient_identifiers()))
 
     def translate_from(self, src_expansion, src_coeff_exprs, src_rscale,
             dvec, tgt_rscale, sac=None, m2l_translation_classes_dependent_data=None):

sumpy/qbx.py

@@ -105,12 +105,12 @@ def _expand(self, sac, avec, bvec, rscale, isrc):
     def _evaluate(self, sac, avec, bvec, rscale, expansion_nr, coefficients):
         from sumpy.expansion.local import LineTaylorLocalExpansion
         tgt_knl = self.target_kernels[expansion_nr]
-        if isinstance(tgt_knl, LineTaylorLocalExpansion):
+        if isinstance(self.expansion, LineTaylorLocalExpansion):
             # In LineTaylorLocalExpansion.evaluate, we can't run
             # postprocess_at_target because the coefficients are assigned
             # symbols and postprocess with a derivative will make them zero.
             # Instead run postprocess here before the coefficients are assigned.
-            coefficients = [tgt_knl.postprocess_at_target(coeff, bvec) for
+            coefficients = [tgt_knl.postprocess_at_target(coeff, avec) for
                     coeff in coefficients]
 
         assigned_coeffs = [