-extern double (*func_f_def) (lmm_variable_t, double);
-extern double (*func_fp_def) (lmm_variable_t, double);
-extern double (*func_fpi_def) (lmm_variable_t, double);
+extern XBT_PRIVATE double (*func_f_def) (lmm_variable_t, double);
+extern XBT_PRIVATE double (*func_fp_def) (lmm_variable_t, double);
+extern XBT_PRIVATE double (*func_fpi_def) (lmm_variable_t, double);