corr_constrain.hpp

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#ifndef STAN_MATH_PRIM_CONSTRAINT_CORR_CONSTRAIN_HPP
#define STAN_MATH_PRIM_CONSTRAINT_CORR_CONSTRAIN_HPP
 
#include <stan/math/prim/meta.hpp>
#include <stan/math/prim/fun/log1m.hpp>
#include <stan/math/prim/fun/square.hpp>
#include <stan/math/prim/fun/sum.hpp>
#include <stan/math/prim/fun/tanh.hpp>
#include <cmath>
 
namespace stan {
namespace math {
 
template <typename T>
inline plain_type_t<T> corr_constrain(const T& x) {
  return tanh(x);
}
 
template <typename T_x, typename T_lp>
inline auto corr_constrain(const T_x& x, T_lp& lp) {
  plain_type_t<T_x> tanh_x = tanh(x);
  lp += sum(log1m(square(tanh_x)));
  return tanh_x;
}
 
template <bool Jacobian, typename T_x, typename T_lp>
inline auto corr_constrain(const T_x& x, T_lp& lp) {
  if (Jacobian) {
    return corr_constrain(x, lp);
  } else {
    return corr_constrain(x);
  }
}
 
}  // namespace math
}  // namespace stan
#endif