From 94c00fc3926360064ecaaf0d5a750a50e0b0539c Mon Sep 17 00:00:00 2001
From: Wolfgang Bangerth <bangerth@math.tamu.edu>
Date: Wed, 23 Mar 2016 17:13:08 -0500
Subject: [PATCH] Simplify some manifold code.

The previous code precomputed a global flag whether the manifold
is periodic or not, but ultimately had to check each coordinate
direction manually anyway. So do away with the global flag, and
simplify the code structure somewhat.
---
 source/grid/manifold.cc | 43 ++++++++++++++++++++---------------------
 1 file changed, 21 insertions(+), 22 deletions(-)

diff --git a/source/grid/manifold.cc b/source/grid/manifold.cc
index 80f4aa9970..9f18fe8d81 100644
--- a/source/grid/manifold.cc
+++ b/source/grid/manifold.cc
@@ -246,37 +246,36 @@ get_new_point (const Quadrature<spacedim> &quad) const
   const std::vector<Point<spacedim> > &surrounding_points = quad.get_points();
   const std::vector<double> &weights = quad.get_weights();
 
-  Point<spacedim> p;
-  Point<spacedim> dp;
   Point<spacedim> minP = periodicity;
-  const bool check_period = (periodicity.norm() > tolerance);
-  if (check_period)
-    for (unsigned int i=0; i<surrounding_points.size(); ++i)
-      for (unsigned int d=0; d<spacedim; ++d)
+
+  for (unsigned int d=0; d<spacedim; ++d)
+    if (periodicity[d] > 0)
+      for (unsigned int i=0; i<surrounding_points.size(); ++i)
         {
           minP[d] = std::min(minP[d], surrounding_points[i][d]);
-          if (periodicity[d] > 0)
-            Assert( (surrounding_points[i][d] < periodicity[d]+tolerance*periodicity.norm()) ||
-                    (surrounding_points[i][d] >= -tolerance*periodicity.norm()),
-                    ExcPeriodicBox(d, surrounding_points[i], periodicity, tolerance*periodicity.norm()));
+          Assert( (surrounding_points[i][d] < periodicity[d]+tolerance*periodicity.norm()) ||
+                  (surrounding_points[i][d] >= -tolerance*periodicity.norm()),
+                  ExcPeriodicBox(d, surrounding_points[i], periodicity, tolerance*periodicity.norm()));
         }
 
+  // compute the weighted average point, possibly taking into account periodicity
+  Point<spacedim> p;
   for (unsigned int i=0; i<surrounding_points.size(); ++i)
     {
-      dp = Point<spacedim>();
-      if (check_period)
-        {
-          for (unsigned int d=0; d<spacedim; ++d)
-            if (periodicity[d] > 0)
-              dp[d] = ( (surrounding_points[i][d]-minP[d]) > periodicity[d]/2.0 ?
-                        -periodicity[d] : 0.0 );
-        }
+      Point<spacedim> dp;
+      for (unsigned int d=0; d<spacedim; ++d)
+        if (periodicity[d] > 0)
+          dp[d] = ( (surrounding_points[i][d]-minP[d]) > periodicity[d]/2.0 ?
+                    -periodicity[d] : 0.0 );
+
       p += (surrounding_points[i]+dp)*weights[i];
     }
-  if (check_period)
-    for (unsigned int d=0; d<spacedim; ++d)
-      if (periodicity[d] > 0)
-        p[d] = (p[d] < 0 ? p[d] + periodicity[d] : p[d]);
+
+  // if necessary, also adjust the weighted point by the periodicity
+  for (unsigned int d=0; d<spacedim; ++d)
+    if (periodicity[d] > 0)
+      if (p[d] < 0)
+        p[d] += periodicity[d];
 
   return project_to_manifold(surrounding_points, p);
 }
-- 
2.39.5