code: public static double logcdf(double val, double loc, double scale, double shape1, double shape2) {
      return logcdf((val - loc) / scale, shape1, shape2);
    }
docs: Cumulative density function.
  
  @param val Value
  @param loc Location
  @param scale Scale
  @param shape1 Shape parameter
  @param shape2 Shape parameter
  @return CDF