- //avoid a disaster value of res_fpi
- if(res_fpi < 0.0) return 0.0;
- else return sqrt(res_fpi);
+ res_fpi = 1/(var->df*var->df*x) - 2/(3*var->df*var->df);
+ if(res_fpi<=0.0) return 0.0;
+ xbt_assert0(res_fpi>0.0,"Don't call me with stupid values!");
+ return sqrt(res_fpi);