Don't compare floating point numbers directly, but via std::fabs.

diff --git a/examples/step-42/step-42.cc b/examples/step-42/step-42.cc
index 8567b2429ff0d1b9554f739db89ae595103daeab..1453429020ab3a67cfc1939bd5ff07219105df7e 100644 (file)
--- a/examples/step-42/step-42.cc
+++ b/examples/step-42/step-42.cc
@@ -952,14 +952,14 @@ namespace Step42
                ++face_no)
             if (cell->face(face_no)->at_boundary())
               {
-                if (cell->face(face_no)->center()[2] == p2(2))
+                if (std::fabs(cell->face(face_no)->center()[2] - p2[2]) < 1e-12)
                   cell->face(face_no)->set_boundary_id(1);
-                if (cell->face(face_no)->center()[0] == p1(0)
-                    || cell->face(face_no)->center()[0] == p2(0)
-                    || cell->face(face_no)->center()[1] == p1(1)
-                    || cell->face(face_no)->center()[1] == p2(1))
+                if (std::fabs(cell->face(face_no)->center()[0] - p1[0]) < 1e-12
+                    || std::fabs(cell->face(face_no)->center()[0] - p2[0]) < 1e-12
+                    || std::fabs(cell->face(face_no)->center()[1] - p1[1]) < 1e-12
+                    || std::fabs(cell->face(face_no)->center()[1] - p2[1]) < 1e-12)
                   cell->face(face_no)->set_boundary_id(8);
-                if (cell->face(face_no)->center()[2] == p1(2))
+                if (std::fabs(cell->face(face_no)->center()[2] - p1[2]) < 1e-12)
                   cell->face(face_no)->set_boundary_id(6);
               }
       }