bool writeCCSMatrix(const string &filename, int rows, int cols, const int *Ap, const int *Ai, const double *Ax, bool upperTriangleSymmetric)
bool writeTripletMatrix(const std::string &filename, int nz, int rows, int cols, const int *Ai, const int *Aj, const double *Ax, bool upperTriangleSymmetric)
TripletEntry(int r_, int c_, double x_)