text: // This file is part of Eigen, a lightweight C++ template library
  // for linear algebra.
  //
  // Copyright (C) 2010 Benoit Jacob <jacob.benoit.1@gmail.com>
  //
  // This Source Code Form is subject to the terms of the Mozilla
  // Public License v. 2.0. If a copy of the MPL was not distributed
  // with this file, You can obtain one at http://mozilla.org/MPL/2.0/.
  
  #ifndef EIGEN_STRIDE_H
  #define EIGEN_STRIDE_H
  
  namespace Eigen {
  
  /** \class Stride
    * \ingroup Core_Module
    *
    * \brief Holds strides information for Map
    *
    * This class holds the strides information for mapping arrays with strides with class Map.
    *
    * It holds two values: the inner stride and the outer stride.
    *
    * The inner stride is the pointer increment between two consecutive entries within a given row of a
    * row-major matrix or within a given column of a column-major matrix.
    *
    * The outer stride is the pointer increment between two consecutive rows of a row-major matrix or
    * between two consecutive columns of a column-major matrix.
    *
    * These two values can be passed either at compile-time as template parameters, or at runtime as
    * arguments to the constructor.
    *
    * Indeed, this class takes two template parameters:
    *  \param _OuterStrideAtCompileTime the outer stride, or Dynamic if you want to specify it at runtime.
    *  \param _InnerStrideAtCompileTime the inner stride, or Dynamic if you want to specify it at runtime.
    *
    * Here is an example:
    * \include Map_general_stride.cpp
    * Output: \verbinclude Map_general_stride.out
    *
    * \sa class InnerStride, class OuterStride, \ref TopicStorageOrders
    */
    template<int _OuterStrideAtCompileTime, int _InnerStrideAtCompileTime>
    class Stride {
    public:
      typedef DenseIndex Index;
      enum {
        InnerStrideAtCompileTime = _InnerStrideAtCompileTime,
        OuterStrideAtCompileTime = _OuterStrideAtCompileTime
      };
  
      /** Default constructor, for use when strides are fixed at compile time */
      Stride()
          : m_outer(OuterStrideAtCompileTime), m_inner(InnerStrideAtCompileTime) {
        eigen_assert(InnerStrideAtCompileTime != Dynamic && OuterStrideAtCompileTime != Dynamic);
      }
  
      /** Constructor allowing to pass the strides at runtime */
      Stride(Index outerStride, Index innerStride)
          : m_outer(outerStride), m_inner(innerStride) {
        eigen_assert(innerStride >= 0 && outerStride >= 0);
      }
  
      /** Copy constructor */
      Stride(const Stride &other)
          : m_outer(other.outer()), m_inner(other.inner()) {}
  
      /** \returns the outer stride */
      inline Index outer() const { return m_outer.value(); }
  
      /** \returns the inner stride */
      inline Index inner() const { return m_inner.value(); }
  
    protected:
      internal::variable_if_dynamic <Index, OuterStrideAtCompileTime> m_outer;
      internal::variable_if_dynamic <Index, InnerStrideAtCompileTime> m_inner;
    };
  
  /** \brief Convenience specialization of Stride to specify only an inner stride
    * See class Map for some examples */
    template<int Value = Dynamic>
    class InnerStride : public Stride<0, Value> {
      typedef Stride<0, Value> Base;
    public:
      typedef DenseIndex Index;
  
      InnerStride() : Base() {}
  
      InnerStride(Index v) : Base(0, v) {}
    };
  
  /** \brief Convenience specialization of Stride to specify only an outer stride
    * See class Map for some examples */
    template<int Value = Dynamic>
    class OuterStride : public Stride<Value, 0> {
      typedef Stride<Value, 0> Base;
    public:
      typedef DenseIndex Index;
  
      OuterStride() : Base() {}
  
      OuterStride(Index v) : Base(v, 0) {}
    };
  
  } // end namespace Eigen
  
  #endif // EIGEN_STRIDE_H
  