// g2o - General Graph Optimization
// Copyright (C) 2011 R. Kuemmerle, G. Grisetti, W. Burgard
// All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
// * Redistributions of source code must retain the above copyright notice,
//   this list of conditions and the following disclaimer.
// * Redistributions in binary form must reproduce the above copyright
//   notice, this list of conditions and the following disclaimer in the
//   documentation and/or other materials provided with the distribution.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
// IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
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#ifndef G2O_MATRIX_STRUCTURE_H
#define G2O_MATRIX_STRUCTURE_H


namespace g2o {

/**
 * \brief representing the structure of a matrix in column compressed structure (only the upper triangular part of the matrix)
 */
class MatrixStructure
{
  public:
    MatrixStructure();
    ~MatrixStructure();
    /**
     * allocate space for the Matrix Structure. You may call this on an already allocated struct, it will
     * then reallocate the memory + additional space (double the required space).
     */
    void alloc(int n_, int nz);

    void free();
    
    /**
     * Write the matrix pattern to a file. File is also loadable by octave, e.g., then use spy(matrix)
     */
    bool write(const char* filename) const;

    int n;    ///< A is m-by-n.  n must be >= 0.
    int m;    ///< A is m-by-n.  m must be >= 0.
    int* Ap;  ///< column pointers for A, of size n+1
    int* Aii; ///< row indices of A, of size nz = Ap [n]

    //! max number of non-zeros blocks
    int nzMax() const { return maxNz;}

  protected:
    int maxN;     ///< size of the allocated memory
    int maxNz;    ///< size of the allocated memory
};

} // end namespace

#endif
