The error in ULPs has a spike around `x = 1/2`: <img width="1486" height="474" alt="Image" src="https://github.com/user-attachments/assets/d954a87b-efe7-4bb8-880a-d4edad2c54ae" /> The left base of the spike: <img width="1504" height="482" alt="Image" src="https://github.com/user-attachments/assets/794df127-0642-44d4-92ad-9d5915cf4033" /> The right base of the spike: <img width="1499" height="482" alt="Image" src="https://github.com/user-attachments/assets/f4a0b76a-3bd6-457b-a4c5-373145fbbfe7" />