const struct categoricals * covariance_get_categoricals (const struct covariance *cov);
-void covariance_get_var_indices (const struct covariance *cov, struct variable **vars);
+void covariance_get_var_indices (const struct covariance *cov, const struct variable **vars);
size_t covariance_dim (const struct covariance * cov);
#endif