The notes to pi in ancient literature from Han to Qing dynasties are quite different, so the concept of pi was not clear for a long time.

自汉代始，历代文献中对铍的注释存在很大分歧，以致长期以来铍的概念一直模糊不清。

youdao

The notes to pi in ancient literature from Han to Qing dynasties are quite different, so the concept of pi was not clear for a long time.

自汉代始，历代文献中对铍的注释存在很大分歧，以致长期以来铍的概念一直模糊不清。

youdao