--- /dev/null
+/* -*- C++ -*- ------------------------------------------------------------
+
+Copyright (c) 2007 Jesse Anders and Demian Nave http://cmldev.net/
+
+The Configurable Math Library (CML) is distributed under the terms of the
+Boost Software License, v1.0 (see cml/LICENSE for details).
+
+ *-----------------------------------------------------------------------*/
+/** @file
+ * @brief
+ *
+ * @todo Currently, the transpose() and T() functions copy the transposed
+ * result into a temporary, and return it to avoid aliasing problems, e.g.
+ * C = transpose(C). By checking for C on the right-hand side, this can
+ * be avoided, but experimentation is needed to determine the impact on
+ * performance. Another option is to use a function to explicitly specify
+ * when a temporary is needed; e.g. C = transpose(temp(C)).
+ */
+
+#ifndef matrix_transpose_h
+#define matrix_transpose_h
+
+#include <cml/matrix/matrix_expr.h>
+
+#define MATRIX_TRANSPOSE_RETURNS_TEMP
+
+namespace cml {
+namespace et {
+
+/** "Transpose" the given matrix expression.
+ *
+ * This does nothing more than change the result type of the expression
+ * into one with the opposite orientation (i.e. row->col, col->row).
+ */
+template<class ExprT>
+class MatrixTransposeOp
+{
+ public:
+
+ typedef MatrixTransposeOp<ExprT> expr_type;
+
+ /* Record ary-ness of the expression: */
+ typedef unary_expression expr_ary;
+
+ /* Copy the expression by value into higher-up expressions: */
+ typedef expr_type expr_const_reference;
+
+ typedef typename ExprT::value_type value_type;
+ typedef matrix_result_tag result_tag;
+ typedef typename ExprT::size_tag size_tag;
+
+ /* Store the expression traits: */
+ typedef ExprTraits<ExprT> expr_traits;
+
+ /* Get the reference type: */
+ typedef typename expr_traits::const_reference expr_reference;
+
+ /* Swap the orientation: */
+ typedef typename expr_traits::result_type::transposed_type result_type;
+
+ /* Get the temporary type: */
+ typedef typename result_type::temporary_type temporary_type;
+
+ /* For matching by assignability: */
+ typedef cml::et::not_assignable_tag assignable_tag;
+
+
+ public:
+
+ /** Record result size as an enum. */
+ enum {
+ array_rows = result_type::array_rows,
+ array_cols = result_type::array_cols
+ };
+
+
+ public:
+
+ /** Return the expression size as a pair. */
+ matrix_size size() const {
+ return matrix_size(this->rows(),this->cols());
+ }
+
+ /** Return result rows.
+ *
+ * The tranpose has the same number of rows as the original has
+ * columns.
+ */
+ size_t rows() const {
+ return expr_traits().cols(m_expr);
+ }
+
+ /** Return result cols.
+ *
+ * The tranpose has the same number of columns as the original has
+ * rows.
+ */
+ size_t cols() const {
+ return expr_traits().rows(m_expr);
+ }
+
+ /** Return reference to contained expression. */
+ expr_reference expression() const { return m_expr; }
+
+ /** Compute value at index i of the result matrix.
+ *
+ * Element (i,j) of the transpose is element (j,i) of the original
+ * expression.
+ */
+ value_type operator()(size_t i, size_t j) const {
+ return expr_traits().get(m_expr,j,i);
+ }
+
+
+ public:
+
+ /** Construct from the subexpression to store. */
+ explicit MatrixTransposeOp(const ExprT& expr) : m_expr(expr) {}
+
+ /** Copy constructor. */
+ MatrixTransposeOp(const expr_type& e) : m_expr(e.m_expr) {}
+
+
+ protected:
+
+ expr_reference m_expr;
+
+
+ private:
+
+ /* Cannot be assigned to: */
+ expr_type& operator=(const expr_type&);
+};
+
+/** Expression traits class for VectorTransposeOp<>. */
+template<class ExprT>
+struct ExprTraits< MatrixTransposeOp<ExprT> >
+{
+ typedef MatrixTransposeOp<ExprT> expr_type;
+ typedef typename expr_type::value_type value_type;
+ typedef typename expr_type::expr_const_reference const_reference;
+ typedef typename expr_type::result_tag result_tag;
+ typedef typename expr_type::size_tag size_tag;
+ typedef typename expr_type::result_type result_type;
+ typedef typename expr_type::assignable_tag assignable_tag;
+ typedef expr_node_tag node_tag;
+
+ value_type get(const expr_type& m, size_t i, size_t j) const {
+ return m(i,j);
+ }
+
+ matrix_size size(const expr_type& e) const { return e.size(); }
+ size_t rows(const expr_type& e) const { return e.rows(); }
+ size_t cols(const expr_type& e) const { return e.cols(); }
+};
+
+} // namespace et
+
+
+/* Define the transpose operators in the cml namespace: */
+#if defined(MATRIX_TRANSPOSE_RETURNS_TEMP)
+
+/** Matrix transpose operator taking a matrix operand. */
+template<typename E, class AT, typename BO, typename L>
+typename et::MatrixTransposeOp<
+ matrix<E,AT,BO,L>
+>::temporary_type
+transpose(const matrix<E,AT,BO,L>& expr)
+{
+ /* Record the matrix type: */
+ typedef matrix<E,AT,BO,L> matrix_type;
+
+ /* Record the type of the transpose op: */
+ typedef et::MatrixTransposeOp<matrix_type> Op;
+
+ /* Determine the returned matrix type: */
+ typedef typename et::MatrixTransposeOp<
+ matrix_type
+ >::temporary_type tmp_type;
+
+ /* The expression to use to assign the temporary: */
+ typedef et::MatrixXpr<Op> ExprT;
+
+ /* Create the temporary and return it: */
+ tmp_type tmp;
+ cml::et::detail::Resize(tmp,expr.rows(),expr.cols());
+ tmp = ExprT(Op(expr));
+ return tmp;
+}
+
+/** Matrix transpose operator taking an et::MatrixXpr operand.
+ *
+ * The parse tree is automatically compressed by hoisting the MatrixXpr's
+ * subexpression into the subexpression of the MatrixTransposeOp.
+ */
+template<class XprT>
+typename et::MatrixTransposeOp<
+ XprT
+>::temporary_type
+transpose(MATXPR_ARG_TYPE expr)
+{
+ /* Record the type of the transpose op: */
+ typedef et::MatrixTransposeOp<XprT> Op;
+
+ /* Determine the returned matrix type: */
+ typedef typename et::MatrixTransposeOp<XprT>::temporary_type tmp_type;
+
+ /* The expression to use to assign the temporary: */
+ typedef et::MatrixXpr<Op> ExprT;
+
+ /* Create the temporary and return it: */
+ tmp_type tmp;
+ cml::et::detail::Resize(tmp,expr.rows(),expr.cols());
+ tmp = ExprT(Op(expr.expression()));
+ return tmp;
+}
+
+
+/* For notational convenience: */
+
+/** Matrix transpose operator taking a matrix operand. */
+template<typename E, class AT, typename BO, typename L>
+typename et::MatrixTransposeOp<
+ matrix<E,AT,BO,L>
+>::temporary_type
+T(const matrix<E,AT,BO,L>& expr)
+{
+ return transpose(expr);
+}
+
+/** Matrix transpose operator taking an et::MatrixXpr operand.
+ *
+ * The parse tree is automatically compressed by hoisting the MatrixXpr's
+ * subexpression into the subexpression of the MatrixTransposeOp.
+ */
+template<class XprT>
+typename et::MatrixTransposeOp<
+ XprT
+>::temporary_type
+T(MATXPR_ARG_TYPE expr)
+{
+ return transpose(expr);
+}
+
+#else
+
+/* XXX For this to work correctly, matrix assignment and copy have to be
+ * changed to either use a temporary all the time, or to create a temporary
+ * when the same matrix appears on both sides of an assignment, and a
+ * temporary was not already created on the RHS by the ET code.
+ */
+
+/** Matrix transpose operator taking a matrix operand. */
+template<typename E, class AT, typename BO, typename L>
+et::MatrixXpr< et::MatrixTransposeOp< matrix<E,AT,BO,L> > >
+transpose(const matrix<E,AT,BO,L>& expr)
+{
+ typedef et::MatrixTransposeOp< matrix<E,AT,BO,L> > ExprT;
+ return et::MatrixXpr<ExprT>(ExprT(expr));
+}
+
+/** Matrix transpose operator taking an et::MatrixXpr operand.
+ *
+ * The parse tree is automatically compressed by hoisting the MatrixXpr's
+ * subexpression into the subexpression of the MatrixTransposeOp.
+ */
+template<class XprT>
+et::MatrixXpr< et::MatrixTransposeOp<XprT> >
+transpose(MATXPR_ARG_TYPE expr)
+{
+ typedef et::MatrixTransposeOp<XprT> ExprT;
+ return et::MatrixXpr<ExprT>(ExprT(expr.expression()));
+}
+
+
+/* For notational convenience: */
+
+/** Matrix transpose operator taking a matrix operand. */
+template<typename E, class AT, typename BO, typename L>
+et::MatrixXpr< et::MatrixTransposeOp< matrix<E,AT,BO,L> > >
+T(const matrix<E,AT,BO,L>& expr)
+{
+ return transpose(expr);
+}
+
+/** Matrix transpose operator taking an et::MatrixXpr operand.
+ *
+ * The parse tree is automatically compressed by hoisting the MatrixXpr's
+ * subexpression into the subexpression of the MatrixTransposeOp.
+ */
+template<class XprT>
+et::MatrixXpr< et::MatrixTransposeOp<XprT> >
+T(MATXPR_ARG_TYPE expr)
+{
+ return transpose(expr);
+}
+
+#endif
+
+} // namespace cml
+
+#endif
+
+// -------------------------------------------------------------------------
+// vim:ft=cpp
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