unsigned rows = m->rows;
unsigned len = rows * cols;
pbqp_matrix_t *copy = (pbqp_matrix_t*)obstack_alloc(&pbqp->obstack, sizeof(*copy) + sizeof(*copy->entries) * len);
unsigned rows = m->rows;
unsigned len = rows * cols;
pbqp_matrix_t *copy = (pbqp_matrix_t*)obstack_alloc(&pbqp->obstack, sizeof(*copy) + sizeof(*copy->entries) * len);