text: #ifndef STAN_MATH_PRIM_PROB_LOGISTIC_RNG_HPP
  #define STAN_MATH_PRIM_PROB_LOGISTIC_RNG_HPP
  
  #include <stan/math/prim/meta.hpp>
  #include <stan/math/prim/err.hpp>
  #include <stan/math/prim/fun/max_size.hpp>
  #include <boost/random/exponential_distribution.hpp>
  #include <boost/random/variate_generator.hpp>
  #include <cmath>
  
  namespace stan {
  namespace math {
  
  /** \ingroup prob_dists
   * Return a Logistic random variate for the given location and scale
   * using the specified random number generator.
   *
   * mu and sigma can each be a scalar or a one-dimensional container. Any
   * non-scalar inputs must be the same size.
   *
   * @tparam T_loc Type of location parameter
   * @tparam T_scale Type of scale parameter
   * @tparam RNG type of random number generator
   * @param mu (Sequence of) location parameter(s)
   * @param sigma (Sequence of) scale parameter(s)
   * @param rng random number generator
   * @return (Sequence of) Logistic random variate(s)
   * @throw std::domain_error if mu is infinite or sigma is nonpositive
   * @throw std::invalid_argument if non-scalar arguments are of different
   * sizes
   */
  template <typename T_loc, typename T_scale, class RNG>
  inline typename VectorBuilder<true, double, T_loc, T_scale>::type logistic_rng(
      const T_loc& mu, const T_scale& sigma, RNG& rng) {
    using boost::random::exponential_distribution;
    using boost::variate_generator;
    static const char* function = "logistic_rng";
  
    check_finite(function, "Location parameter", mu);
    check_positive_finite(function, "Scale parameter", sigma);
    check_consistent_sizes(function, "Location parameter", mu, "Scale Parameter",
                           sigma);
  
    scalar_seq_view<T_loc> mu_vec(mu);
    scalar_seq_view<T_scale> sigma_vec(sigma);
    size_t N = max_size(mu, sigma);
    VectorBuilder<true, double, T_loc, T_scale> output(N);
  
    variate_generator<RNG&, exponential_distribution<> > exp_rng(
        rng, exponential_distribution<>(1));
    for (size_t n = 0; n < N; ++n) {
      output[n] = mu_vec[n] - sigma_vec[n] * std::log(exp_rng() / exp_rng());
    }
  
    return output.data();
  }
  
  }  // namespace math
  }  // namespace stan
  #endif
  