copysign.hpp

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#ifndef STAN_MATH_PRIM_SCAL_FUN_COPYSIGN_HPP
#define STAN_MATH_PRIM_SCAL_FUN_COPYSIGN_HPP
 
#include <stan/math/prim/meta.hpp>
#include <stan/math/prim/fun/value_of_rec.hpp>
#include <cmath>
#include <complex>
 
namespace stan {
namespace math {
 
template <typename T, typename U>
inline T copysign(const T& x, const U& y) {
  return (std::signbit(value_of_rec(x)) != std::signbit(value_of_rec(y))) ? -x
                                                                          : x;
}
 
template <typename T, typename U>
inline T copysign_non_zero(const T& x, const U& y) {
  return x != 0 ? stan::math::copysign(x, y) : x;
}
 
template <typename T, typename U>
inline std::complex<T> copysign(const std::complex<T>& x,
                                const std::complex<U>& y) {
  return {copysign_non_zero(x.real(), y.real()),
          copysign_non_zero(x.imag(), y.imag())};
}
 
}  // namespace math
}  // namespace stan
 
#endif