From 5b2fea880f67aecfb8c786e817c8beef9c8c76ef Mon Sep 17 00:00:00 2001
From: Wolfgang Bangerth <bangerth@math.tamu.edu>
Date: Tue, 2 Jul 2013 19:36:17 +0000
Subject: [PATCH] Use a non-recursive version of the unroll function.

git-svn-id: https://svn.dealii.org/trunk@29919 0785d39b-7218-0410-832d-ea1e28bc413d
---
 deal.II/include/deal.II/base/tensor.h | 31 ++++++++++++++-------------
 1 file changed, 16 insertions(+), 15 deletions(-)

diff --git a/deal.II/include/deal.II/base/tensor.h b/deal.II/include/deal.II/base/tensor.h
index dc5dd68407..eaceaee41b 100644
--- a/deal.II/include/deal.II/base/tensor.h
+++ b/deal.II/include/deal.II/base/tensor.h
@@ -605,14 +605,13 @@ inline
 unsigned int
 Tensor<rank_, dim, Number>::component_to_unrolled_index(const TableIndices<rank_> &indices)
 {
-   TableIndices<rank_-1> indices1;
-   for (unsigned int i = 0; i < rank_-1;i++)
-   	 indices1[i] = indices[i];
-
-   Assert (indices[rank_-1] < dim,
-	   ExcIndexRange (indices[rank_-1], 0, dim));
-   return ( Tensor<rank_-1,dim,Number>::component_to_unrolled_index(indices1) * dim + indices[rank_-1]);
+  TableIndices<rank_-1> indices1;
+  for (unsigned int i = 0; i < rank_-1;i++)
+    indices1[i] = indices[i];
 
+  Assert (indices[rank_-1] < dim,
+	  ExcIndexRange (indices[rank_-1], 0, dim));
+  return ( Tensor<rank_-1,dim,Number>::component_to_unrolled_index(indices1) * dim + indices[rank_-1]);
 }
 
 template <int rank_, int dim, typename Number>
@@ -620,16 +619,18 @@ inline
 TableIndices<rank_>
 Tensor<rank_, dim, Number>::unrolled_to_component_indices(const unsigned int i)
 {
-  TableIndices<rank_-1> indices1;
-  TableIndices<rank_>   indices;
+  Assert (i < n_independent_components,
+	  ExcIndexRange (i, 0, n_independent_components));
 
-  indices[rank_-1] = (i % dim);
-  const unsigned int i1 = i / dim;
-
-  indices1 = Tensor<rank_-1,dim,Number>::unrolled_to_component_indices(i1);
+  TableIndices<rank_>   indices;
 
-  for (unsigned int i = 0; i < rank-1;i++)
-    indices[i] = indices1[i];
+  unsigned int remainder = i;
+  for (int r=rank_-1; r>=0; ++r)
+    {
+      indices[r] = (remainder % dim);
+      remainder /= dim;
+    }
+  Assert (remainder == 0, ExcInternalError());
 
   return indices;
 }
-- 
2.39.5