log1p.hpp

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#ifndef STAN_MATH_PRIM_FUN_LOG1P_HPP
#define STAN_MATH_PRIM_FUN_LOG1P_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/is_nan.hpp>
#include <stan/math/prim/functor/apply_scalar_unary.hpp>
#include <cmath>
 
namespace stan {
namespace math {
 
inline double log1p(double x) {
  if (is_nan(x)) {
    return x;
  } else {
    check_greater_or_equal("log1p", "x", x, -1.0);
    return std::log1p(x);
  }
}
 
inline double log1p(int x) {
  check_greater_or_equal("log1p", "x", x, -1);
  return std::log1p(x);
}
 
struct log1p_fun {
  template <typename T>
  static inline auto fun(const T& x) {
    return log1p(x);
  }
};
 
template <typename T,
          require_not_nonscalar_prim_or_rev_kernel_expression_t<T>* = nullptr,
          require_not_var_matrix_t<T>* = nullptr>
inline auto log1p(const T& x) {
  return apply_scalar_unary<log1p_fun, T>::apply(x);
}
 
}  // namespace math
}  // namespace stan
 
#endif