Abu Mansur Abd al-Qahir ibn Tahir ibn Muhammad ibn Abdallah al-Tamimi al-Shaffi al-Baghdadi (Arabic: أبو منصور عبدالقاهر ابن طاهر بن محمد بن عبدالله التميمي الشافعي البغدادي‎) was an Arabian mathematician (c. 980–1037) from Baghdad who is best known for his treatise al-Takmila fi'l-Hisab. It contains results in number theory, and comments on works by al-Khwarizmi which are now lost.
See also

List of Arab scientists and scholars.

References

O'Connor, John J.; Robertson, Edmund F., "Abu Mansur ibn Tahir Al-Baghdadi", MacTutor History of Mathematics archive, University of St Andrews.
Biography of Imam Al Baghdadi by at-tawhid.net