REGISTER_GRADIENT_OP("Acosh", AcoshGrad);

Status AtanhGrad(const Scope& scope, const Operation& op,
                 const std::vector<Output>& grad_inputs,
                 std::vector<Output>* grad_outputs) {
  // y = atanh(x)
  // dy/dx = 1 / (1 - x^2)
  auto one = Cast(scope, Const(scope, 1.0), op.input(0).type());
  auto dydx = Reciprocal(scope, Sub(scope, one, Square(scope, op.input(0))));
  // grad(x) = grad(y) * conj(dy/dx)

      new absl::flat_hash_map<string, std::vector<string>>{
          // Unary
          {"PW",
           {"ComplexAbs", "Angle", "Conj", "Abs", "Acos", "Acosh", "Asin",
            "Atan", "Atanh", "Ceil", "Cos", "Cosh", "Sin", "Exp", "Expm1",
            "Floor", "IsFinite", "IsInf", "IsNan", "Inv", "Reciprocal", "Log",
            "Log1p", "Invert", "LogicalNot", "Ndtri", "Neg", "Rint", "Round",