public static double logcdf(double x,double k,double theta,double shift){
  x=(x - shift);
  if (x <= 0.) {
    return 0.;
  }
  return GammaDistribution.logregularizedGammaP(k,Math.log1p(x) * theta);
}

public static double logcdf ( double x , double k , double theta , double shift ) { x = ( x - shift ) ; if ( x <= 0. ) { return 0. ; } return GammaDistribution . logregularizedGammaP ( k , Math . log1p ( x ) * theta ) ; }
the log cdf , static version .
