2 int **i_idx,
int **j_idx,
double **a);
4 int **row_start,
int **col_idx,
double **a);
6 int *row_start,
int *col_idx,
double *a);
void read_hb_matrix(char *fn, int *m, int *n, int *nz, int **row_start, int **col_idx, double **a)
void write_csr(char *fn, int m, int n, int nz, int *row_start, int *col_idx, double *a)
void read_mm_matrix(char *fn, int *m, int *n, int *nz, int **i_idx, int **j_idx, double **a)