[reductors.residual] fix for riesz calculation

pymor · Jan 31, 2019 · c75eaea · c75eaea
1 parent f441a79
commit c75eaea
Showing 1 changed file with 8 additions and 2 deletions.
diff --git a/src/pymor/reductors/residual.py b/src/pymor/reductors/residual.py
@@ -153,9 +153,15 @@ def apply(self, U, mu=None):
         if self.product:
             if self.riesz_representatives:
                 R_riesz = self.product.apply_inverse(R)
-                return R_riesz * (np.sqrt(R_riesz.dot(R)) / R_riesz.l2_norm())[0]
+                # divide by norm, except when norm is zero:
+                inversel2 = 1./R_riesz.l2_norm()
+                inversel2 = np.nan_to_num(inversel2)
+                return R_riesz * (np.sqrt(R_riesz.dot(R)) * inversel2)[0]
             else:
-                return R * (np.sqrt(self.product.pairwise_apply2(R, R)) / R.l2_norm())[0]
+                # divide by norm, except when norm is zero:
+                inversel2 = 1./R.l2_norm()
+                inversel2 = np.nan_to_num(inversel2)
+                return R * (np.sqrt(self.product.pairwise_apply2(R, R)) * inversel2)[0]
         else:
             return R