From: Matthias Maier <tamiko@43-1.org>
Date: Tue, 1 Sep 2015 22:43:56 +0000 (-0500)
Subject: Tensor<k,dim>: Remove superfluous operator* variants
X-Git-Tag: v8.4.0-rc2~466^2~34
X-Git-Url: https://gitweb.dealii.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=5c64397fda6c14327e789d0aba8c8a73f899b569;p=dealii.git

Tensor<k,dim>: Remove superfluous operator* variants

It is completely sufficient to provide 1 ("one") templated variant.

I guess, over time more and more variants were added. This increased the
grade of ambiguity for the compiler to chose the one intended
implementation.
---

diff --git a/include/deal.II/base/tensor.h b/include/deal.II/base/tensor.h
index e03b76da2b..2aa0744d7f 100644
--- a/include/deal.II/base/tensor.h
+++ b/include/deal.II/base/tensor.h
@@ -1977,236 +1977,6 @@ linfty_norm (const Tensor<2,dim,Number> &t)
 
 
 
-/**
- * Multiplication of a tensor of general rank with a scalar Number from the
- * right.
- *
- * @relates Tensor
- */
-template <int rank, int dim, typename Number>
-inline
-Tensor<rank,dim,Number>
-operator * (const Tensor<rank,dim,Number> &t,
-            const Number                   factor)
-{
-  Tensor<rank,dim,Number> tt = t;
-  tt *= factor;
-  return tt;
-}
-
-
-
-/**
- * Multiplication of a tensor of general rank with a scalar Number from the
- * left.
- *
- * @relates Tensor
- */
-template <int rank, int dim, typename Number>
-inline
-Tensor<rank,dim,Number>
-operator * (const Number                   factor,
-            const Tensor<rank,dim,Number> &t)
-{
-  Tensor<rank,dim,Number> tt = t;
-  tt *= factor;
-  return tt;
-}
-
-
-#ifndef DEAL_II_WITH_CXX11
-
-template <typename T, typename U, int rank, int dim>
-struct ProductType<T,Tensor<rank,dim,U> >
-{
-  typedef Tensor<rank,dim,typename ProductType<T,U>::type> type;
-};
-
-template <typename T, typename U, int rank, int dim>
-struct ProductType<Tensor<rank,dim,T>,U>
-{
-  typedef Tensor<rank,dim,typename ProductType<T,U>::type> type;
-};
-
-#endif
-
-
-/**
- * Multiplication of a tensor of general rank with a scalar number from the
- * right.
- *
- * The purpose of this operator is to enable only multiplication of a tensor
- * by a scalar number (i.e., a floating point number, a complex floating point
- * number, etc.). The function is written in a way that only allows the
- * compiler to consider the function if the second argument is indeed a scalar
- * number -- in other words, @p OtherNumber will not match, for example
- * <code>std::vector@<double@></code> as the product of a tensor and a vector
- * clearly would make no sense. The mechanism by which the compiler is
- * prohibited of considering this operator for multiplication with non-scalar
- * types are explained in the documentation of the EnableIfScalar class.
- *
- * The return type of the function is chosen so that it matches the types of
- * both the tensor and the scalar argument. For example, if you multiply a
- * <code>Tensor@<1,dim,double@></code> by <code>std::complex@<double@></code>,
- * then the result will be a
- * <code>Tensor@<1,dim,std::complex@<double@>@></code>. In other words, the
- * type with which the returned tensor stores its components equals the type
- * you would get if you multiplied an individual component of the input tensor
- * by the scalar factor.
- *
- * @relates Tensor
- * @relates EnableIfScalar
- */
-template <int rank, int dim, typename Number, typename OtherNumber>
-inline
-Tensor<rank,dim,typename ProductType<Number,typename EnableIfScalar<OtherNumber>::type>::type>
-operator * (const Tensor<rank,dim,Number> &t,
-            const OtherNumber              factor)
-{
-  // recurse over the base objects
-  Tensor<rank,dim,typename ProductType<Number,OtherNumber>::type> tt;
-  for (unsigned int d=0; d<dim; ++d)
-    tt[d] = t[d] * factor;
-  return tt;
-}
-
-
-
-/**
- * Multiplication of a tensor of general rank with a scalar number from the
- * left. See the discussion with the operator with switched arguments for more
- * information about template arguments and the return type.
- *
- * @relates Tensor
- * @relates EnableIfScalar
- */
-template <int rank, int dim, typename Number, typename OtherNumber>
-inline
-Tensor<rank,dim,typename ProductType<Number,typename EnableIfScalar<OtherNumber>::type>::type>
-operator * (const Number                        factor,
-            const Tensor<rank,dim,OtherNumber> &t)
-{
-  // simply forward to the operator above
-  return t * factor;
-}
-
-
-
-/**
- * Division of a tensor of general rank by a scalar Number.
- *
- * @relates Tensor
- */
-template <int rank, int dim, typename Number>
-inline
-Tensor<rank,dim,Number>
-operator / (const Tensor<rank,dim,Number> &t,
-            const Number                   factor)
-{
-  Tensor<rank,dim,Number> tt = t;
-  tt /= factor;
-  return tt;
-}
-
-
-
-
-/**
- * Multiplication of a tensor of general rank with a scalar double from the
- * right.
- *
- * @relates Tensor
- */
-template <int rank, int dim>
-inline
-Tensor<rank,dim>
-operator * (const Tensor<rank,dim> &t,
-            const double            factor)
-{
-  Tensor<rank,dim> tt = t;
-  tt *= factor;
-  return tt;
-}
-
-
-
-/**
- * Multiplication of a tensor of general rank with a scalar double from the
- * left.
- *
- * @relates Tensor
- */
-template <int rank, int dim>
-inline
-Tensor<rank,dim>
-operator * (const double            factor,
-            const Tensor<rank,dim> &t)
-{
-  Tensor<rank,dim> tt = t;
-  tt *= factor;
-  return tt;
-}
-
-
-
-/**
- * Division of a tensor of general rank by a scalar double.
- *
- * @relates Tensor
- */
-template <int rank, int dim>
-inline
-Tensor<rank,dim>
-operator / (const Tensor<rank,dim> &t,
-            const double            factor)
-{
-  Tensor<rank,dim> tt = t;
-  tt /= factor;
-  return tt;
-}
-
-
-
-/**
- * Multiplication of a tensor of general rank by a scalar complex<double> from
- * the left.
- *
- * @relates Tensor
- */
-template <int rank, int dim>
-inline
-Tensor<rank,dim,std::complex<double> >
-operator * (const std::complex<double>  factor,
-            const Tensor<rank,dim>     &t)
-{
-  Tensor<rank,dim,std::complex<double> > tt;
-  for (unsigned int d=0; d<dim; ++d)
-    tt[d] = factor * t[d];
-  return tt;
-}
-
-
-
-/**
- * Multiplication of a tensor of general rank by a scalar complex<double> from
- * the right.
- *
- * @relates Tensor
- */
-template <int rank, int dim>
-inline
-Tensor<rank,dim,std::complex<double> >
-operator * (const Tensor<rank,dim>     &t,
-            const std::complex<double>  factor)
-{
-  Tensor<rank,dim,std::complex<double> > tt;
-  for (unsigned int d=0; d<dim; ++d)
-    tt[d] = t[d] * factor;
-  return tt;
-}
-
-
-
 DEAL_II_NAMESPACE_CLOSE
 
 #endif
diff --git a/include/deal.II/base/tensor_base.h b/include/deal.II/base/tensor_base.h
index 6a5f04e89b..3971045115 100644
--- a/include/deal.II/base/tensor_base.h
+++ b/include/deal.II/base/tensor_base.h
@@ -1284,6 +1284,7 @@ Tensor<1,dim,Number>::memory_consumption ()
 }
 
 
+
 template <int dim, typename Number>
 template <class Archive>
 inline
@@ -1294,6 +1295,7 @@ void Tensor<1,dim,Number>::serialize(Archive &ar, const unsigned int)
 #endif // DOXYGEN
 
 
+
 /**
  * Output operator for tensors of rank 0. Since such tensors are scalars, we
  * simply print this one value.
@@ -1346,61 +1348,26 @@ std::ostream &operator << (std::ostream &out, const Tensor<1,1,double> &p)
 
 
 
-/**
- * Multiplication of a tensor of rank 1 with a scalar Number from the right.
- *
- * @relates Tensor<1,dim,Number>
- */
-template <int dim, typename Number>
-inline
-Tensor<1,dim,Number>
-operator * (const Tensor<1,dim,Number> &t,
-            const Number                factor)
-{
-  Tensor<1,dim,Number> tt (false);
-  for (unsigned int d=0; d<dim; ++d)
-    tt[d] = t[d] * factor;
-  return tt;
-}
-
-
-
-/**
- * Multiplication of a tensor of rank 1 with a scalar Number from the left.
- *
- * @relates Tensor<1,dim,Number>
- */
-template <int dim, typename Number>
-inline
-Tensor<1,dim,Number>
-operator * (const Number                factor,
-            const Tensor<1,dim,Number> &t)
-{
-  Tensor<1,dim,Number> tt (false);
-  for (unsigned int d=0; d<dim; ++d)
-    tt[d] = t[d] * factor;
-  return tt;
-}
-
-
 #ifndef DEAL_II_WITH_CXX11
 
-template <typename T, typename U, int dim>
-struct ProductType<T,Tensor<1,dim,U> >
+template <typename T, typename U, int rank, int dim>
+struct ProductType<T,Tensor<rank,dim,U> >
 {
-  typedef Tensor<1,dim,typename ProductType<T,U>::type> type;
+  typedef Tensor<rank,dim,typename ProductType<T,U>::type> type;
 };
 
-template <typename T, typename U, int dim>
-struct ProductType<Tensor<1,dim,T>,U>
+template <typename T, typename U, int rank, int dim>
+struct ProductType<Tensor<rank,dim,T>,U>
 {
-  typedef Tensor<1,dim,typename ProductType<T,U>::type> type;
+  typedef Tensor<rank,dim,typename ProductType<T,U>::type> type;
 };
 
 #endif
 
+
+
 /**
- * Multiplication of a tensor of rank 1 with a scalar number from the right.
+ * Multiplication of a tensor of rank with a scalar number from the right.
  *
  * The purpose of this operator is to enable only multiplication of a tensor
  * by a scalar number (i.e., a floating point number, a complex floating point
@@ -1421,80 +1388,20 @@ struct ProductType<Tensor<1,dim,T>,U>
  * you would get if you multiplied an individual component of the input tensor
  * by the scalar factor.
  *
- * @relates Tensor<1,dim,Number>
- * @relates EnableIfScalar
- */
-template <int dim, typename Number, typename OtherNumber>
-inline
-Tensor<1,dim,typename ProductType<Number,typename EnableIfScalar<OtherNumber>::type>::type>
-operator * (const Tensor<1,dim,Number> &t,
-            const OtherNumber           factor)
-{
-  // form the product. we have to convert the two factors into the final
-  // type via explicit casts because, for awkward reasons, the C++
-  // standard committee saw it fit to not define an
-  //   operator*(float,std::complex<double>)
-  // (as well as with switched arguments and double<->float).
-  typedef typename ProductType<Number,OtherNumber>::type product_type;
-  Tensor<1,dim,product_type> tt (false);
-  for (unsigned int d=0; d<dim; ++d)
-    tt[d] = product_type(t[d]) * product_type(factor);
-  return tt;
-}
-
-
-
-/**
- * Multiplication of a tensor of rank 1 with a scalar number from the left.
- * See the discussion with the operator with switched arguments for more
- * information about template arguments and the return type.
- *
- * @relates Tensor<1,dim,Number>
+ * @relates Tensor
  * @relates EnableIfScalar
  */
-template <int dim, typename Number, typename OtherNumber>
+template <int rank, int dim,
+         typename Number,
+         typename OtherNumber,
+         typename = typename EnableIfScalar<OtherNumber>::type>
 inline
-Tensor<1,dim,typename ProductType<Number,typename EnableIfScalar<OtherNumber>::type>::type>
-operator * (const Number                     factor,
-            const Tensor<1,dim,OtherNumber> &t)
+Tensor<rank,dim,typename ProductType<Number, OtherNumber>::type>
+operator * (const Tensor<rank,dim,Number> &t,
+            const OtherNumber              factor)
 {
-  // simply forward to the other operator with switched arguments
-  return (t*factor);
-}
-
-
-
-/**
- * Division of a tensor of rank 1 by a scalar Number.
- *
- * @relates Tensor<1,dim,Number>
- */
-template <int dim, typename Number>
-inline
-Tensor<1,dim,Number>
-operator / (const Tensor<1,dim,Number> &t,
-            const Number                factor)
-{
-  Tensor<1,dim,Number> tt (false);
-  for (unsigned int d=0; d<dim; ++d)
-    tt[d] = t[d] / factor;
-  return tt;
-}
-
-
-
-/**
- * Multiplication of a tensor of rank 1 with a scalar double from the right.
- *
- * @relates Tensor<1,dim,Number>
- */
-template <int dim>
-inline
-Tensor<1,dim>
-operator * (const Tensor<1,dim> &t,
-            const double         factor)
-{
-  Tensor<1,dim> tt (false);
+  // recurse over the base objects
+  Tensor<rank,dim,typename ProductType<Number,OtherNumber>::type> tt;
   for (unsigned int d=0; d<dim; ++d)
     tt[d] = t[d] * factor;
   return tt;
@@ -1503,36 +1410,47 @@ operator * (const Tensor<1,dim> &t,
 
 
 /**
- * Multiplication of a tensor of rank 1 with a scalar double from the left.
+ * Multiplication of a tensor of general rank with a scalar number from the
+ * left. See the discussion with the operator with switched arguments for more
+ * information about template arguments and the return type.
  *
- * @relates Tensor<1,dim,Number>
+ * @relates Tensor
+ * @relates EnableIfScalar
  */
-template <int dim>
+template <int rank, int dim,
+         typename Number,
+         typename OtherNumber,
+         typename = typename EnableIfScalar<OtherNumber>::type>
 inline
-Tensor<1,dim>
-operator * (const double         factor,
-            const Tensor<1,dim> &t)
+Tensor<rank,dim,typename ProductType<Number, OtherNumber>::type>
+operator * (const Number                        factor,
+            const Tensor<rank,dim,OtherNumber> &t)
 {
-  Tensor<1,dim> tt (false);
-  for (unsigned int d=0; d<dim; ++d)
-    tt[d] = t[d] * factor;
-  return tt;
+  // simply forward to the operator above
+  return t * factor;
 }
 
 
 
 /**
- * Division of a tensor of rank 1 by a scalar double.
+ * Division of a tensor of general rank with a scalar number. See the
+ * discussion on operator*() above for more information about template
+ * arguments and the return type.
  *
- * @relates Tensor<1,dim,Number>
+ * @relates Tensor
+ * @relates EnableIfScalar
  */
-template <int dim>
+template <int rank, int dim,
+         typename Number,
+         typename OtherNumber,
+         typename = typename EnableIfScalar<OtherNumber>::type>
 inline
-Tensor<1,dim>
-operator / (const Tensor<1,dim> &t,
-            const double         factor)
+Tensor<rank,dim,typename ProductType<Number, OtherNumber>::type>
+operator / (const Tensor<rank,dim,Number> &t,
+            const OtherNumber              factor)
 {
-  Tensor<1,dim> tt (false);
+  // recurse over the base objects
+  Tensor<rank,dim,typename ProductType<Number,OtherNumber>::type> tt;
   for (unsigned int d=0; d<dim; ++d)
     tt[d] = t[d] / factor;
   return tt;
@@ -1540,46 +1458,6 @@ operator / (const Tensor<1,dim> &t,
 
 
 
-/**
- * Multiplication of a tensor of rank 1 by a scalar complex<double> from the
- * right.
- *
- * @relates Tensor<1,dim,Number>
- */
-template <int dim>
-inline
-Tensor<1,dim,std::complex<double> >
-operator * (const Tensor<1,dim>        &t,
-            const std::complex<double>  factor)
-{
-  Tensor<1,dim,std::complex<double> > tt (false);
-  for (unsigned int d=0; d<dim; ++d)
-    tt[d] = t[d] * factor;
-  return tt;
-}
-
-
-
-/**
- * Multiplication of a tensor of rank 1 by a scalar complex<double> from the
- * left.
- *
- * @relates Tensor<1,dim,Number>
- */
-template <int dim>
-inline
-Tensor<1,dim,std::complex<double> >
-operator * (const std::complex<double>  factor,
-            const Tensor<1,dim>        &t)
-{
-  Tensor<1,dim,std::complex<double> > tt (false);
-  for (unsigned int d=0; d<dim; ++d)
-    tt[d] = t[d] * factor;
-  return tt;
-}
-
-
-
 DEAL_II_NAMESPACE_CLOSE
 
 #endif