return d->m->size1;
}
+double
+design_matrix_get_element (const struct design_matrix *d, size_t row, size_t col)
+{
+ return (gsl_matrix_get (d->m, row, col));
+}
+void
+design_matrix_set_element (const struct design_matrix *d, size_t row, size_t col, double x)
+{
+ gsl_matrix_set (d->m, row, col, x);
+}