positive_ordered_free.hpp

Go to the documentation of this file.

#ifndef STAN_MATH_PRIM_FUN_POSITIVE_ORDERED_FREE_HPP
#define STAN_MATH_PRIM_FUN_POSITIVE_ORDERED_FREE_HPP
 
#include <stan/math/prim/meta.hpp>
#include <stan/math/prim/err.hpp>
#include <stan/math/prim/fun/Eigen.hpp>
#include <stan/math/prim/fun/log.hpp>
#include <stan/math/prim/fun/to_ref.hpp>
#include <cmath>
 
namespace stan {
namespace math {
 
template <typename EigVec, require_eigen_col_vector_t<EigVec>* = nullptr>
auto positive_ordered_free(const EigVec& y) {
  using std::log;
  const auto& y_ref = to_ref(y);
  check_positive_ordered("stan::math::positive_ordered_free",
                         "Positive ordered variable", y_ref);
  Eigen::Index k = y_ref.size();
  plain_type_t<EigVec> x(k);
  if (k == 0) {
    return x;
  }
  x.coeffRef(0) = log(y_ref.coeff(0));
  x.tail(k - 1)
      = (y_ref.tail(k - 1) - y_ref.head(k - 1)).array().log().matrix();
  return x;
}
 
template <typename T, require_std_vector_t<T>* = nullptr>
auto positive_ordered_free(const T& x) {
  return apply_vector_unary<T>::apply(
      x, [](auto&& v) { return positive_ordered_free(v); });
}
 
}  // namespace math
}  // namespace stan
 
#endif