+
+
+double diff_aux(lmm_variable_t var, double x){
+ double tmp_fp, tmp_fpi, tmp_fpip, result;
+
+ xbt_assert0(var->func_fp, "Initialize the protocol functions first create variables before.");
+
+ tmp_fp = var->func_fp(var, x);
+ tmp_fpi = var->func_fpi(var, x);
+ tmp_fpip = var->func_fpip(var, x);
+
+ result = tmp_fpip*(var->func_fp(var, tmp_fpi));