/* whether modified from previous scan. used after matrix_scan. */
bool matrix_is_modified(void);
/* whether ghosting occur on matrix. */
bool matrix_has_ghost(void);
/* whether a swtich is on */
/* whether modified from previous scan. used after matrix_scan. */
bool matrix_is_modified(void);
/* whether ghosting occur on matrix. */
bool matrix_has_ghost(void);
/* whether a swtich is on */