Phi_approx.hpp

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#ifndef __STAN__MATH__FUNCTIONS__PHI_APPROX_HPP__
#define __STAN__MATH__FUNCTIONS__PHI_APPROX_HPP__

#include <boost/math/tools/promotion.hpp>
#include <stan/math/functions/inv_logit.hpp>

namespace stan {
  namespace math {

    template <typename T>
    inline typename boost::math::tools::promote_args<T>::type
    Phi_approx(T x) {
      return inv_logit(0.07056 * std::pow(x,3.0) + 1.5976 * x);
    }

  }
}

#endif