sign.hpp

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#ifndef STAN_MATH_PRIM_FUN_SIGN_HPP
#define STAN_MATH_PRIM_FUN_SIGN_HPP
 
#include <stan/math/prim/meta.hpp>
#include <stan/math/prim/functor/apply_scalar_unary.hpp>
 
namespace stan {
namespace math {
 
// returns 1 if NaN is passed in.
template <typename T, require_stan_scalar_t<T>* = nullptr>
inline int sign(const T& z) {
  return (z == 0) ? 0 : z < 0 ? -1 : 1;
}
 
struct sign_fun {
  template <typename T>
  static inline int fun(const T& x) {
    return sign(x);
  }
};
 
template <typename T, require_container_t<T>* = nullptr>
inline auto sign(const T& x) {
  return apply_scalar_unary<sign_fun, T>::apply(x);
}
 
}  // namespace math
}  // namespace stan
 
#endif