From: Wolfgang Bangerth <bangerth@math.tamu.edu>
Date: Tue, 12 Apr 2011 20:27:37 +0000 (+0000)
Subject: New operator* between SymmetricTensor and Tensor.
X-Git-Tag: v8.0.0~4176
X-Git-Url: https://gitweb.dealii.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=19237540ff29594a9429f54f4328f051e08d2068;p=dealii.git

New operator* between SymmetricTensor and Tensor.

git-svn-id: https://svn.dealii.org/trunk@23580 0785d39b-7218-0410-832d-ea1e28bc413d
---

diff --git a/deal.II/doc/news/changes.h b/deal.II/doc/news/changes.h
index c8af879b66..76bef4543a 100644
--- a/deal.II/doc/news/changes.h
+++ b/deal.II/doc/news/changes.h
@@ -85,12 +85,17 @@ should be fixed now.
 <h3>Specific improvements</h3>
 
 <ol>
+<li> New: There is now an operator* for the multiplication of a <code>SymmetricTensor@<2,dim@></code>
+and a <code>Tensor@<1,dim@></code>.
+<br>
+(Wolfgang Bangerth, 2011/04/12)
+
 <li> Fixed: Added some instantiations to make KellyErrorEstimator and SolutionTransfer
 work in  codimension one. Fixed some dim in spacedim.
 <br>
 (Luca Heltai, 2011/04/11)
 
-<li> Fixed: Added some instantiations to make anisotropic refinement work 
+<li> Fixed: Added some instantiations to make anisotropic refinement work
 in codimension one.
 <br>
 (Luca Heltai, 2011/03/31)
diff --git a/deal.II/examples/step-46/step-46.cc b/deal.II/examples/step-46/step-46.cc
index 024fe21337..0915fbbb28 100644
--- a/deal.II/examples/step-46/step-46.cc
+++ b/deal.II/examples/step-46/step-46.cc
@@ -480,8 +480,8 @@ void FluidStructureProblem<dim>::assemble_system ()
 		      for (unsigned int i=0; i<stokes_dofs_per_cell; ++i)
 			for (unsigned int j=0; j<elasticity_dofs_per_cell; ++j)
 			  local_matrix(i,j) += (2 * viscosity *
-						contract(stokes_phi_grads_u[i],
-							 normal_vector) *
+						(stokes_phi_grads_u[i] *
+						 normal_vector) *
 						elasticity_phi[j] *
 						stokes_fe_face_values.JxW(q));
 		    }
diff --git a/deal.II/include/deal.II/base/symmetric_tensor.h b/deal.II/include/deal.II/base/symmetric_tensor.h
index 87cdbc047e..51038c2db4 100644
--- a/deal.II/include/deal.II/base/symmetric_tensor.h
+++ b/deal.II/include/deal.II/base/symmetric_tensor.h
@@ -2974,6 +2974,35 @@ double_contract (SymmetricTensor<2,3> &tmp,
 
 
 
+/**
+ * Multiplication operator performing a contraction of the last index
+ * of the first argument and the first index of the second
+ * argument. This function therefore does the same as the
+ * corresponding <tt>contract</tt> function, but returns the result as
+ * a return value, rather than writing it into the reference given as
+ * the first argument to the <tt>contract</tt> function.
+ *
+ * Note that for the <tt>Tensor</tt> class, the multiplication
+ * operator only performs a contraction over a single pair of
+ * indices. This is in contrast to the multiplication operator for
+ * symmetric tensors, which does the double contraction.
+ *
+ * @relates SymmetricTensor
+ * @author Wolfgang Bangerth, 2005
+ */
+template <int dim>
+Tensor<1,dim>
+operator * (const SymmetricTensor<2,dim> &src1,
+            const Tensor<1,dim> &src2)
+{
+  Tensor<1,dim> dest;
+  for (unsigned int i=0; i<dim; ++i)
+    for (unsigned int j=0; j<dim; ++j)
+      dest[i] += src1[i][j] * src2[j];
+  return dest;
+}
+
+
 /**
  * Output operator for symmetric tensors of rank 2. Print the elements
  * consecutively, with a space in between, two spaces between rank 1