/// <summary>
        /// Method to copy the data in this Sparse4DMatrix instance to another instance.
        /// </summary>
        /// <param name="sparse4DMatrix">An instance of the Sparse4DMatrix class.</param>
        public void CopyTo(Sparse4DMatrix <TKey0, TKey1, TKey2, TKey3, TValue> sparse4DMatrix)
        {
            sparse4DMatrix.m_dictionary.Clear();

            // Copy each key value pair to the dictionary.
            foreach (KeyValuePair <ComparableTuple4 <TKey0, TKey1, TKey2, TKey3>, TValue> pair in m_dictionary)
            {
                ComparableTuple4 <TKey0, TKey1, TKey2, TKey3> newCombinedKey = new ComparableTuple4 <TKey0, TKey1, TKey2, TKey3>(pair.Key);
                sparse4DMatrix.m_dictionary.Add(newCombinedKey, pair.Value);
            }
        }
        /// <summary>
        /// Method to copy the data in another Sparse4DMatrix instance to this instance.
        /// </summary>
        /// <param name="sparse4DMatrix">An instance of the Sparse4DMatrix class.</param>
        private void Initialize(Sparse4DMatrix <TKey0, TKey1, TKey2, TKey3, TValue> sparse4DMatrix)
        {
            m_dictionary.Clear();

            // Copy each key value pair to the dictionary.
            foreach (KeyValuePair <ComparableTuple4 <TKey0, TKey1, TKey2, TKey3>, TValue> pair in sparse4DMatrix)
            {
                ComparableTuple4 <TKey0, TKey1, TKey2, TKey3> newCombinedKey = new ComparableTuple4 <TKey0, TKey1, TKey2, TKey3>(pair.Key);
                m_dictionary.Add(newCombinedKey, pair.Value);
            }
        }
 /// <summary>
 /// Copy constructor.
 /// </summary>
 /// <param name="sparse4DMatrix">The sparse array instance to be copied</param>
 public Sparse4DMatrix(Sparse4DMatrix <TKey0, TKey1, TKey2, TKey3, TValue> sparse4DMatrix)
 {
     InitializeDictionary();
     Initialize(sparse4DMatrix);
     DefaultValue = sparse4DMatrix.DefaultValue;
 }