text: #ifndef STAN_MATH_PRIM_MAT_FUN_COSH_HPP
  #define STAN_MATH_PRIM_MAT_FUN_COSH_HPP
  
  #include <stan/math/prim/mat/vectorize/apply_scalar_unary.hpp>
  #include <cmath>
  
  namespace stan {
  namespace math {
  
  /**
   * Structure to wrap cosh() so it can be vectorized.
   * @param x Angle in radians.
   * @tparam T Variable type.
   * @return Hyperbolic cosine of x.
   */
  struct cosh_fun {
    template <typename T>
    static inline T fun(const T& x) {
      using std::cosh;
      return cosh(x);
    }
  };
  
  /**
   * Vectorized version of cosh().
   * @param x Angle in radians.
   * @tparam T Variable type.
   * @return Hyberbolic cosine of x.
   */
  template <typename T>
  inline typename apply_scalar_unary<cosh_fun, T>::return_t cosh(const T& x) {
    return apply_scalar_unary<cosh_fun, T>::apply(x);
  }
  
  }  // namespace math
  }  // namespace stan
  
  #endif
  