// local
#include "Event/ChiSquare.h"
#include "gsl/gsl_cdf.h"

namespace LHCb {
double ChiSquare::prob() const {
  double val(0);
  if (nDoF() > 0) {
    const double limit = 1e-15;
    double chi2max = gsl_cdf_chisq_Qinv(limit, nDoF());
    val = chi2() < chi2max ? gsl_cdf_chisq_Q(chi2(), nDoF()) : 0;
  }
  return val;
}
}