message: Update the comment to match the implementation, as was suggested in review
diff: @@ -1111,12 +1111,13 @@ XlaOp RoundToEven(XlaOp x) {
  // acos(x) = 2 * atan(sqrt(1 - x^2) / (1 + x)) if x != -1
  // pi if x == -1
  +// For complex:
  +// acos(x) = -(i * log(x + i * sqrt((1 + x) * (1 - x))))
  XlaOp Acos(XlaOp x) {
  XlaBuilder* b = x.builder();
  return b->ReportErrorOrReturn([&]() -> StatusOr<XlaOp> {
  TF_ASSIGN_OR_RETURN(auto shape, b->GetShape(x));
  - // complex: acos(x) = -i * log(x + sqrt(-(x+1)*(x-1)))
  if (primitive_util::IsComplexType(shape.element_type())) {
  auto one = ScalarLike(x, 1);
  auto imag_one = Complex(
  