templates - How can I create a sparse matrix as a list of lists? (C++) -

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the question is: possible create sparse matrix using following sparse list implementation? in special, using class template class template (sparselist*>)?

i've created class template named sparselist can add elements in whatever index want.

i'd use create sparsematrix class template. tried following...

//sparsematrix.h  template <typename t> class sparsematrix {     public:         sparsematrix();      private:         sparselist<sparselist<t>*> *matrix;  };  template <typename t> sparsematrix<t>::sparsematrix() {     matrix = new sparselist<sparselist<t>*>(); }

but when try instantiate on main...

int main() {     sparsematrix<int> *matrix;     matrix = new sparsematrix<int>(); //without line compiled normally.      return 0; }

i got following error...

in file included src/main.cpp: sparsematrix.h:   instantiated 'sparsematrix<t>::sparsematrix() [with t = int]' main.cpp:   instantiated here sparselist.h: error: template argument required 'struct sparsematrix'

i'm using netbeanside 6.9.1 mingw.

edit:

//sparselist.h template <typename t> class sparselist {      template <typename u>     friend std::ostream & operator<<(std::ostream &output, const sparselist<u> &list);  public:     sparselist();     virtual ~sparselist();      void insert(t &entry, int index);     t & get(int i);     int length();  private:     struct listnode {         int index;         t *entry;         listnode *next;     };      listnode *head; //pointer first entry in sparse list.     int size; //# of entries. };

i tested inserts , gets, constructors , destructors, in sparselist. working fine... =)

why pointers?

this should job data storage inside class:

std::map<std::pair<i, i>, t>

where i index type (e.g. int) , t number type (e.g. double).

or use compressed_matrix boost::ublas.


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