/*
*
* Template Numerical Toolkit (TNT)
*
* Mathematical and Computational Sciences Division
* National Institute of Technology,
* Gaithersburg, MD USA
*
*
* This software was developed at the National Institute of Standards and
* Technology (NIST) by employees of the Federal Government in the course
* of their official duties. Pursuant to title 17 Section 105 of the
* United States Code, this software is not subject to copyright protection
* and is in the public domain. NIST assumes no responsibility whatsoever for
* its use by other parties, and makes no guarantees, expressed or implied,
* about its quality, reliability, or any other characteristic.
*
*/


#ifndef TNT_SPARSE_MATRIX_CSR_H
#define TNT_SPARSE_MATRIX_CSR_H

#include "tnt_array1d.h"

namespace TNT
{


/**
    Read-only view of a sparse matrix in compressed-row storage
    format.  Neither array elements (nonzeros) nor sparsity
    structure can be modified.  If modifications are required,
    create a new view.

    <p>
    Index values begin at 0.

    <p>
    <b>Storage requirements:</b> An (m x n) matrix with
    nz nonzeros requires no more than  ((T+I)*nz + M*I)
    bytes, where T is the size of data elements and
    I is the size of integers.


*/
template <class T>
class Sparse_Matrix_CompRow {

private:
    Array1D<T>    val_;       // data values (nz_ elements)
    Array1D<int>  rowptr_;    // row_ptr (dim_[0]+1 elements)
    Array1D<int>  colind_;    // col_ind  (nz_ elements)

    int dim1_;        // number of rows
    int dim2_;        // number of cols

public:

    Sparse_Matrix_CompRow(const Sparse_Matrix_CompRow &S);
    Sparse_Matrix_CompRow(int M, int N, int nz, const T *val,
                        const int *r, const int *c);



    inline   const T&      val(int i) const { return val_[i]; }
    inline   const int&         row_ptr(int i) const { return rowptr_[i]; }
    inline   const int&         col_ind(int i) const { return colind_[i];}

    inline   int    dim1() const {return dim1_;}
    inline   int    dim2() const {return dim2_;}
       int          NumNonzeros() const {return val_.dim1();}


    Sparse_Matrix_CompRow& operator=(
                    const Sparse_Matrix_CompRow &R);



};

/**
    Construct a read-only view of existing sparse matrix in
    compressed-row storage format.

    @param M the number of rows of sparse matrix
    @param N the  number of columns of sparse matrix
    @param nz the number of nonzeros
    @param val a contiguous list of nonzero values
    @param r row-pointers: r[i] denotes the beginning position of row i
        (i.e. the ith row begins at val[row[i]]).
    @param c column-indices: c[i] denotes the column location of val[i]
*/
template <class T>
Sparse_Matrix_CompRow<T>::Sparse_Matrix_CompRow(int M, int N, int nz,
    const T *val, const int *r, const int *c) : val_(nz,val),
        rowptr_(M, r), colind_(nz, c), dim1_(M), dim2_(N) {}


}
// namespace TNT

#endif
