Fix bug in MappingQGeneric::transform_real_to_unit_cell

diff --git a/source/fe/mapping_q_generic.cc b/source/fe/mapping_q_generic.cc
index b4e5d22f8b8307918251289332c4d916e4be7317..959445efecbe6e0b8466b13a0a3dcd14fb8f196f 100644 (file)
--- a/source/fe/mapping_q_generic.cc
+++ b/source/fe/mapping_q_generic.cc
@@ -2534,7 +2534,7 @@ MappingQGeneric<dim, spacedim>::transform_real_to_unit_cell(
 {
   // Use an exact formula if one is available. this is only the case
   // for Q1 mappings in 1d, and in 2d if dim==spacedim
-  if ((polynomial_degree == 1) &&
+  if (this->preserves_vertex_locations() && (polynomial_degree == 1) &&
       ((dim == 1) || ((dim == 2) && (dim == spacedim))))
     {
       // The dimension-dependent algorithms are much faster (about 25-45x in