std::vector<Output>* grad_outputs) {
  // y = acosh(x)
  // dy/dx = 1 / sinh(y)
  auto dydx = Reciprocal(scope, Sinh(scope, op.output(0)));
  // grad(x) = grad(y) * conj(dy/dx)
  grad_outputs->push_back(
      Mul(scope, grad_inputs[0], ConjugateHelper(scope, dydx)));
  return scope.status();
}
REGISTER_GRADIENT_OP("Acosh", AcoshGrad);

Status AtanhGrad(const Scope& scope, const Operation& op,

      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",

}

// Complex hyperbolic cosine
//
// DESCRIPTION:
//
// ccosh(z) = cosh x  cos y + i sinh x sin y .
//
// ACCURACY:
//
//                      Relative error:
// arithmetic   domain     # trials      peak         rms
//    IEEE      -10,+10     30000       2.9e-16     8.1e-17

// Cosh returns the hyperbolic cosine of x.
func Cosh(x complex128) complex128 {
	switch re, im := real(x), imag(x); {

	}

	if sign {
		temp = -temp
	}
	return temp
}

// Cosh returns the hyperbolic cosine of x.
//
// Special cases are:
//
//	Cosh(±0) = 1
//	Cosh(±Inf) = +Inf
//	Cosh(NaN) = NaN
func Cosh(x float64) float64 {
	if haveArchCosh {
		return archCosh(x)
	}
	return cosh(x)
}

func cosh(x float64) float64 {
	x = Abs(x)
	if x > 21 {
		return Exp(x) * 0.5
	}
	ex := Exp(x)

		temp = satan(x / temp)
	}

	if sign {
		temp = -temp
	}
	return temp
}

// Acos returns the arccosine, in radians, of x.
//
// Special case is:
//
//	Acos(x) = NaN if x < -1 or x > 1
func Acos(x float64) float64 {
	if haveArchAcos {
		return archAcos(x)
	}
	return acos(x)
}

func acos(x float64) float64 {
	return Pi/2 - Asin(x)

  %0, %1, %2 = "tf.IfRegion"(%arg0) ({
     %t0 = "tf.Abs"(%arg1) : (tensor<2xf32>) -> tensor<2xf32>
     %t1 = "tf.Acos"(%arg1) : (tensor<2xf32>) -> tensor<2xf32>
     %t2 = "tf.Acosh"(%arg1) : (tensor<2xf32>) -> tensor<2xf32>
    "tf.Yield"(%t0, %t1, %t2) : (tensor<2xf32>, tensor<2xf32>, tensor<2xf32>) -> ()
    }, {

	case re == 0 && math.IsNaN(im):
		return x
	}
	d := math.Cos(2*real(x)) + math.Cosh(2*imag(x))
	if math.Abs(d) < 0.25 {
		d = tanSeries(x)
	}
	if d == 0 {
		return Inf()
	}
	return complex(math.Sin(2*real(x))/d, math.Sinh(2*imag(x))/d)
}

// Complex hyperbolic tangent
//
// DESCRIPTION:
//
// tanh z = (sinh 2x  +  i sin 2y) / (cosh 2x + cos 2y) .
//
// ACCURACY:
//
//                      Relative error:

GLOBL coshe5<>+0(SB), RODATA, $8
DATA coshe6<>+0(SB)/8, $0.138926439368309441e-02
GLOBL coshe6<>+0(SB), RODATA, $8

// Cosh returns the hyperbolic cosine of x.
//
// Special cases are:
//      Cosh(±0) = 1
//      Cosh(±Inf) = +Inf
//      Cosh(NaN) = NaN
// The algorithm used is minimax polynomial approximation
// with coefficients determined with a Remez exchange algorithm.

static constexpr char kMlirModuleStr[] = R"(
  module attributes {tf.versions = {bad_consumers = [], min_consumer = 0 : i32, producer = 268 : i32}} {
  func.func @main(%arg0 : tensor<1xf32>) -> tensor<1xf32> {
    %0 = "tf.Acos"(%arg0) : (tensor<1xf32>) -> tensor<1xf32>
   func.return %0 : tensor<1xf32>
  }
})";

static constexpr char kBadMlirModuleStr[] = R"(

DATA ·acosrodataL13<> + 184(SB)/8, $0.157079632679489656e+01
DATA ·acosrodataL13<> + 192(SB)/8, $0.0
GLOBL ·acosrodataL13<> + 0(SB), RODATA, $200

// Acos returns the arccosine, in radians, of the argument.
//
// Special case is:
//      Acos(x) = NaN if x < -1 or x > 1
// The algorithm used is minimax polynomial approximation
// with coefficients determined with a Remez exchange algorithm.