text: #ifndef STAN_MATH_REV_FUN_TRIGAMMA_HPP
  #define STAN_MATH_REV_FUN_TRIGAMMA_HPP
  
  #include <stan/math/rev/meta.hpp>
  #include <stan/math/rev/core.hpp>
  #include <stan/math/rev/fun/floor.hpp>
  #include <stan/math/rev/fun/sin.hpp>
  #include <stan/math/rev/fun/square.hpp>
  #include <stan/math/rev/fun/inv_square.hpp>
  #include <stan/math/prim/scal/fun/trigamma.hpp>
  
  namespace stan {
  namespace math {
  
  /**
   * Return the value of the trigamma function at the specified
   * argument (i.e., the second derivative of the log Gamma function
   * at the specified argument).
   *
   * @param u argument
   * @return trigamma function at argument
   */
  inline var trigamma(const var& u) { return trigamma_impl(u); }
  
  }  // namespace math
  }  // namespace stan
  #endif
  